diff --git a/CHANGELOG.md b/CHANGELOG.md
index ba00439..7a6a626 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -108,6 +108,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   retry/timeout options
 - Extracted the duplicated request-timing/instrumentation/rescue logic in
   `get_from_api`/`post_to_api` into a shared `perform_request` helper
+- **Breaking**: Removed POST support (`Service#api_post_json`/`post_json`/
+  `post_to_api`). Confirmed unused by both consuming apps (`ppd-explorer`,
+  `ukhpi`); GET is the only HTTP method the gem now sends, so `method` is no
+  longer part of `request.data_services_api`'s payload
 
 ## 1.7.0 - 2026-07-13
 
diff --git a/README.md b/README.md
index d61863f..63586e2 100644
--- a/README.md
+++ b/README.md
@@ -244,9 +244,9 @@ configured `instrumenter`:
   fields via its own accessors, e.g. `env.method`, `env.url`), so a
   subscriber to this event needs different handling than the rest.
 - **`request.data_services_api`** - fires immediately before a request is
-  sent (both GET and POST), regardless of how it later resolves.
+  sent, regardless of how it later resolves.
 - **`response.data_services_api`** - fires for every response that doesn't
-  raise (both GET and POST).
+  raise.
 - **`connection_failure.data_services_api`** - a network-level failure
   (timeout or refused connection), after retries are exhausted. The request
   never got a response at all.
@@ -267,7 +267,7 @@ the event doesn't include that field):
 | `exception` | see note | - | - | - | `Faraday::TimeoutError`/`ConnectionFailed` | `ServiceException` | see note |
 | `path` | `String` (bare path, no scheme/host/query) | - | ✓ | -<sup>‡</sup> | ✓ | ✓ | ✓ |
 | `query_string` | `String`, nilable<sup>§</sup> | - | ✓ | -<sup>‡</sup> | ✓ | ✓ | - |
-| `method` | `String`, upcased | - | ✓ | -<sup>‡</sup> | - | - | ✓ |
+| `method` | `String`, upcased | - | - | -<sup>‡</sup> | - | - | ✓ |
 | `status` | `Integer`, nilable | - | - | -<sup>‡</sup> | always `503` | nilable<sup>¶</sup> | - |
 | `duration` | `Integer`, **milliseconds** | - | - | ✓ | ✓ | ✓ | - |
 | `will_retry_in` | `Float`, **seconds** | - | - | - | - | - | ✓ |
@@ -279,8 +279,7 @@ Hash - none of these field names apply; see above.<br>
 <sup>‡</sup> derivable from the `response:`/`exception:` object already in
 the payload rather than duplicated as a separate field - see the code
 examples below.<br>
-<sup>§</sup> `nil` for POST requests (which never have query params) and for
-GET requests with no params.<br>
+<sup>§</sup> `nil` for GET requests with no params.<br>
 <sup>¶</sup> `nil` if Faraday never associated a response with the error
 (`Faraday::Error#response_status` returns `nil` in that case - can happen
 for some `Faraday::ParsingError`s).
diff --git a/lib/data_services_api/service.rb b/lib/data_services_api/service.rb
index 4f7c8a2..85d2171 100644
--- a/lib/data_services_api/service.rb
+++ b/lib/data_services_api/service.rb
@@ -64,10 +64,6 @@ def api_get_json(api, params, options = {})
       get_json(as_http_api(api), params, options)
     end
 
-    def api_post_json(api, json)
-      post_json(as_http_api(api), json)
-    end
-
     private
 
     # Get parsed JSON from the given URL
@@ -78,7 +74,7 @@ def get_json(http_url, params, options)
     def get_from_api(http_url, accept_headers, params, options)
       query_params = params.merge(options)
 
-      perform_request(http_url, 'GET', query_params) do |conn|
+      perform_request(http_url, query_params) do |conn|
         conn.get do |req|
           req.headers['X-Request-Id'] = Thread.current[:request_id] if Thread.current[:request_id]
           req.headers['Accept'] = accept_headers
@@ -88,28 +84,14 @@ def get_from_api(http_url, accept_headers, params, options)
       end
     end
 
-    def post_json(http_url, json)
-      post_to_api(http_url, json).body
-    end
-
-    def post_to_api(http_url, json)
-      perform_request(http_url, 'POST') do |conn|
-        conn.post do |req|
-          req.headers['X-Request-Id'] = Thread.current[:request_id] if Thread.current[:request_id]
-          req.headers['Accept'] = 'application/json'
-          req.headers['Content-Type'] = 'application/json'
-          req.body = json
-        end
-      end
-    end
-
-    # Perform an HTTP request against http_url, timing and instrumenting it consistently
-    # regardless of whether it succeeds, times out, fails to connect, or the remote API
-    # returns an error status or unparseable body. query_params, when given, is only used
-    # to report the query string on connection/service failures (a successful response
-    # reports its own resolved query string from the Faraday response itself)
-    def perform_request(http_url, method, query_params = nil) # rubocop:disable Metrics/MethodLength
-      instrument_request(http_url, method, query_params)
+    # Perform an HTTP GET request against http_url, timing and instrumenting it
+    # consistently regardless of whether it succeeds, times out, fails to connect,
+    # or the remote API returns an error status or unparseable body. query_params
+    # is only used to report the query string on connection/service failures (a
+    # successful response reports its own resolved query string from the Faraday
+    # response itself)
+    def perform_request(http_url, query_params) # rubocop:disable Metrics/MethodLength
+      instrument_request(http_url, query_params)
 
       start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC, :microsecond)
       conn = create_http_connection(http_url)
@@ -211,14 +193,12 @@ def instrument_response(response, start_time)
     end
 
     # Fires 'request.data_services_api' immediately before a request is sent.
-    # Payload: path (String, no scheme/host/query), method (String, upcased),
-    # and query_string (String or nil - nil for POST requests, which never pass
-    # query_params, and for GET requests with no params).
-    def instrument_request(http_url, method, query_params)
+    # Payload: path (String, no scheme/host/query) and query_string (String or
+    # nil - nil for GET requests with no params).
+    def instrument_request(http_url, query_params)
       instrumenter&.instrument(
         'request.data_services_api',
         path: URI.parse(http_url).path,
-        method:,
         query_string: query_params && URI.encode_www_form(query_params)
       )
     end
@@ -227,10 +207,9 @@ def instrument_request(http_url, method, query_params)
     # (after retries are exhausted): the request never got a response at all.
     # Payload: exception (Faraday::TimeoutError or ConnectionFailed), path
     # (String, no scheme/host/query), query_string (String or nil - nil for
-    # POST requests, which never pass query_params, and for GET requests with
-    # no params), duration (Integer milliseconds, see #instrument_response),
-    # and status (always the literal 503 - a fixed value, not derived from any
-    # actual response, since none was received).
+    # GET requests with no params), duration (Integer milliseconds, see
+    # #instrument_response), and status (always the literal 503 - a fixed
+    # value, not derived from any actual response, since none was received).
     def instrument_connection_failure(http_url, query_params, exception, start_time)
       instrumenter&.instrument(
         'connection_failure.data_services_api',
diff --git a/sig/data_services_api/service.rbs b/sig/data_services_api/service.rbs
index 5f9e2f2..47b9d4d 100644
--- a/sig/data_services_api/service.rbs
+++ b/sig/data_services_api/service.rbs
@@ -29,14 +29,10 @@ module DataServicesApi
 
     def initialize: (?::Hash[untyped, untyped] config) -> void
 
-    def datasets: () -> Array[Dataset]
-
     def dataset: (untyped name) -> Dataset
 
     def api_get_json: (untyped api, untyped params, ?::Hash[untyped, untyped] options) -> json_value
 
-    def api_post_json: (untyped api, untyped json) -> json_value
-
     private
 
     # Get parsed JSON from the given URL
@@ -44,16 +40,13 @@ module DataServicesApi
 
     def get_from_api: (untyped http_url, untyped accept_headers, untyped params, untyped options) -> untyped
 
-    def post_json: (untyped http_url, untyped json) -> untyped
-
-    def post_to_api: (untyped http_url, untyped json) -> untyped
-
-    # Perform an HTTP request against http_url, timing and instrumenting it consistently
-    # regardless of whether it succeeds, times out, fails to connect, or the remote API
-    # returns an error status or unparseable body. query_params, when given, is only used
-    # to report the query string on connection/service failures (a successful response
-    # reports its own resolved query string from the Faraday response itself)
-    def perform_request: (untyped http_url, untyped method, ?untyped? query_params) { (untyped) -> untyped } -> untyped
+    # Perform an HTTP GET request against http_url, timing and instrumenting it
+    # consistently regardless of whether it succeeds, times out, fails to connect,
+    # or the remote API returns an error status or unparseable body. query_params
+    # is only used to report the query string on connection/service failures (a
+    # successful response reports its own resolved query string from the Faraday
+    # response itself)
+    def perform_request: (untyped http_url, untyped query_params) { (untyped) -> untyped } -> untyped
 
     def create_http_connection: (untyped http_url) -> untyped
 
@@ -72,10 +65,9 @@ module DataServicesApi
     def instrument_retry: (untyped env, untyped retry_count, untyped exception, untyped will_retry_in) -> untyped
 
     # Fires 'request.data_services_api' immediately before a request is sent, with
-    # path (String), method (String), and query_string (String or nil - nil for
-    # POST requests, which never pass query_params, and for GET requests with
+    # path (String) and query_string (String or nil - nil for GET requests with
     # no params).
-    def instrument_request: (untyped http_url, untyped method, untyped query_params) -> untyped
+    def instrument_request: (untyped http_url, untyped query_params) -> untyped
 
     def as_http_api: (untyped api) -> untyped
 
@@ -90,8 +82,7 @@ module DataServicesApi
     # (after retries are exhausted): the request never got a response at all.
     # Payload: exception (Faraday::TimeoutError or ConnectionFailed), path
     # (String, no scheme/host/query), query_string (String or nil - nil for
-    # POST requests, which never pass query_params, and for GET requests with
-    # no params), duration (Integer milliseconds, see #instrument_response),
+    # GET requests with no params), duration (Integer milliseconds, see #instrument_response),
     # and status (always the literal 503 - a fixed value, not derived from any
     # actual response, since none was received).
     def instrument_connection_failure: (untyped http_url, untyped query_params, untyped exception, untyped start_time) -> untyped
diff --git a/test/data_services_api/service_test.rb b/test/data_services_api/service_test.rb
index 67289a5..b7855e3 100644
--- a/test/data_services_api/service_test.rb
+++ b/test/data_services_api/service_test.rb
@@ -131,7 +131,6 @@ def instrument(*args)
 
     _, payload = mock_notifier.instrumentations.find { |name, _| name == 'request.data_services_api' }
     _(payload).wont_be_nil
-    _(payload[:method]).must_equal 'GET'
     _(payload[:path]).must_equal '/landregistry/id/ukhpi'
     _(payload[:query_string]).must_equal '_limit=1'
   end