Sophos Central API Token Request

Hi everyone,

I'm planning to add some Sophos API functions into an in-house application written in C#. At the moment I'm just working on a scratch app so that I can test code for authenticating, getting a token etc. without affecting live code, but I'm struggling to get a token from the API. The code so far looks like this:

                try
                {
                    using (var client = new HttpClient())
                    {
                        var body = $"grant_type=client_credentials&client_id={SophosClientID}&client_secret={SophosClientSecret}&scope=token";
                        using (var msg = new HttpRequestMessage
                        {
                            RequestUri = new Uri(SophosAPIUrl), // https://id.sophos.com/api/v2/oauth2/token
                            Method = HttpMethod.Post,
                            Content = new StringContent(body, Encoding.UTF8, "application/x-www-form-urlencoded")
                        })
                        {
                            var result = client.SendAsync(msg).GetAwaiter().GetResult();
                            if(result != null)
                            {
                                var token = result.Content.ReadAsStringAsync().GetAwaiter().GetResult();
                                UpdateTextBox(token);
                            }
                            else
                            {
                                UpdateTextBox("Result was null");
                            }
                        }
                    }
                }
                catch(Exception ex)
                {
                    UpdateTextBox($"Process failed: {ex.Message}");
                }

The values for SophosClientID and SophosClientSecret are from the API credentials page. I've test with CURL and it works OK but the code above always returns a "Bad Request" error. I'd be grateful for any advice/tips on how to get this working.

Andy