This is a quote from a book called The Assessment of Advanced Motorcycling
"Failing to observe a speed limit will result in a test failure
all signs must be seen and complied with
the speedometer is permitted to show the speed limit and up to 4MPH over, but not continually in excess
when in the national speed limit, and above still applies, however, if the is a vehicle ahead travelling below that limit it should be overtaken at a suitable opportunity. In these circumstances the overtake takes priority over the speed limit, only for the duration of the overtake and with due discretion. (if there is a line of vehicles to be overtaken then each vehicle should be assessed in turn but not necessarily overtaken individually - the should not go blasting passed all of them because they are travelling at 57MPH)."
When I went to a RoSPA Talk from a RoSPA examiner(ex police rider) he clearly stated you can not speed on an overtake but when he took me on my test I was told to ask about this, his answer was "as long has the speed is not to excessive". So I agree with Both Mark And Fred, Add a bit of extra speed to do the overtake but it doesn't need to be much just enough to get passed safely then return to the speed limit.
