SNS3Guppy, The reason I asked was because under UK aviation law, you need a written permission to go above 250 kts in Class G airspace. I don't think ATC can give ad hoc permission on the day; Class G doesn't "belong" to ATC.
If you don't have it then don't be surprised if folk complain. I know one corporate operator who was warned off and threatened with further action for flying over 250kts. The evidence was his mode S transponder readout.