Hornby 5 pole skew motor

[125_driver]

Firstly, apologies this may seem a daft question, but one that is bugging me!

The Hornby current HST and the current class 87 are both powered by 5 pole skew wound motors. HOWEVER, whilst the HST runs a lovely scale 125mph and then some, the 87 I have found far far slower. This isn't an isolated example or a dodgy motor, so my question is why if they have the same motor is one so slow compared to the other?

 

My guess would be gearing, but just thought I'd put it on here, as I find the slowness of the WCML racehorses disappointing on my high speed layout.

 

Finally, is the new class 91 likely to be set to the HST speed or the slower 87 speed??

 

Any help appreciated! Thanks.