on the 737 the min clean is around 210-220 kts.Selecting VNAV will set the commanded speed at 250 kts.The speed restriction of 250kts/FL100 is set in the FMC ,and it's our SOP to follow that if not otherwise requested by the ATC.This will give the highest ROC to FL 100 ,most of the time.
The climb speed will be 280 kts( if turbulence expected) or something around 300 kts .
In London TMA,having to stop at FL60, we'll have to mantain 250 kts for a longer period of time.From what I've got from you,ATCO people,a higher speed will help by getting us faster out of your TMA. Of course ,with this trials that you've talked about ,things must be diff.
And,no,no-one told us at our comp about those trials you're doing at London TMA.