Hate to differ but in Class D/E airspace below FL100 the speed limit of 250kts is manditory there is no ATC disgression
Assuming we are talking about the UK here, (the reference to 'RA service' and questions about EGLL ops imply a UK perspective), then you are incorrect.
In the UK, the restriction may be lifted in Class D at the discretion of ATC. My answer was drawn from the UK Manual of Air Traffic Services.
"None IS correct" - "none" is singular.
Quite right, I hang my head.