Why are only police and prison officers getting a pay rise?

A Guardian letters correspondent has a theory:

The decision to release the pay cap only for police and prison officers will inevitably attract strong criticism from nurses and others, but it makes sense. Most Tory MPs probably have private healthcare, but they might well need the services of the police to intervene between them and the electorate during the conference season and beyond. Tory peers should also support the decision; Lords Archer, Hanningfield and Taylor of Warwick [Tory peers who have spent time in prison] could tell them how helpful prison officers can be at difficult times.

Geoff Booth

Knebworth, Hertfordshire”