That's an interesting one Syy.
From an ATC training point of view it could be a good 'oral-board question'.
According to the airspace classification table in the ENR section of the UK AIP, Class D airspace has a 250kt restriction below FL100, (similar to most of the SIDs), where as Class A has no such restriction (unless ATC tell you otherwise).
Some SIDS also have a much longer set of speed restrictions called a 'Speed Profile', which specify speeds to be flown up to about FL290. The LISTO and SANBA SIDs from EGCC carry these restrictions, as well as the longer one on the SAM from 'KK.
Although neither of the above points directly answer your question, and any revised ATC clearance automatically cancels the previous clearance, I would still say stick with the 250kts unless told otherwise. It's a few years since I did it, but in the NW of England at least, ATC still usually volunteer the information anyway, but..'If in doubt, always ask'.
Last edited by ZOOKER; 10th Nov 2017 at 08:23.