UK serial allocation for F35

I was looking through the UK Serials website:

http://www.ukserials.com/

And noted that only 65 serials have been allocated to the F35 in the ZM range:

ZM135 – ZM200

This is far less then the stated planed buy of 150 but very close to the stated minimum number required to operate off the new carriers.

Are we seeing the first clear signs of cutbacks?!