The creation of some of the allowances had a legitimate purpose, and teh use of them for that purpose is right. For example an MP would be reduced in the work done for constituents without an office and staff.

I suspect the second housing allowance was another Thatcher gerrymander - to assist the backwoodsmen to attend when every seat in London was red. Yet I think it has merit in principle. MPs should live in their constituencies in order better to represent them, yet they also need to be near Westminster when parliament is sitting.

Plainly though, to the common man, it is the central London home that is the second home, and that should be so for all purposes. Indeed maybe an approprate allowance for that purpose should be limited to rent.

Help with maintaining the moat on the ancestral pile, or building up a property empire, or keeping one's expensive daughter is a different kettle of fish.