You make a good point BB. If (and it is still an if) the allowances package make the Mon-Fri commute/live in Pimlico option unattractive or unavailable, it will have several impacts:
a. The demand for London MQs will increase (at significant cost).
b. Commuting expenses will increase.
c. Personnel will be less willing to work into the late evening if they have to commute (not necessarily a bad thing as the self-flagellation mindset in MB is appalling)
d. Manning will have far more difficulty in filling Centre jobs.
As this is being done to save money, it is the first 2 impacts that are likely to cause big problems further downstream. Unfortunately, that may all be too late.