Enterprise console > migrate to new server

I've been moving Sophos Enterprise Console from an old WS2003 box over to a new 2012R2 box, using the Sophos server to server migration guide. All seemed to be well untill I tried starting the console on the new server. It would try to connect but time out after a while. with the error

Sophos.UIController.Extension.UIControllerException: Cannot retrieve session token after 8 retries. Please check that the Management Host Service is running

Nothing shows in the windows event logs and all services are started ok.

I then went on to double check the registry keys and console settings to make sure all was pointing at the new, as well as all the good stuff in KBA118513 but all seems to be as it should.

interestingly in the IdentityService log there's multiple warnings:

2015-02-13 14:22:50,479 [21] [(null)] WARN  {SophosManagementSecurity.InvokeManagementServiceOperation} ==> Management service is not available [Reason = System.InvalidCastException: Unable to cast COM object of type 'ManagementServiceLib.CoreServicesClass' to interface type 'ManagementServiceLib.ISM_ManagementServiceApp'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{66A41465-AA37-4E13-9610-49A5D9BB948C}' failed due to the following error: The RPC server is unavailable. (Exception from HRESULT: 0x800706BA).

at System.StubHelpers.StubHelpers.GetCOMIPFromRCW(Object objSrc, IntPtr pCPCMD, IntPtr& ppTarget, Boolean& pfNeedsRelease

at ManagementServiceLib.CoreServicesClass.getSubEstates(String username)

at Sophos.Management.Security.RoleBaseAdministrationAdaptor.<>c__DisplayClass9.<FetchAndVerifyUserSubEstate>b__5()

at Sophos.Management.Security.RoleBaseAdministrationAdaptor.InvokeManagementServiceOperation[T](Func`1 func, String machineUserName, Int32 numberOfRetries)].

this seems to be the only evidence that something is wrong. Any ideas what could be causing this? Am I missing something obvious?