[Margaret Pilkington]

You make a valid point when you ask if drivers over 70 were banned then they would be at the mercy of public transport. Of course the answer is Yes, they would.....and you may say that that is Ok then as they have the free bus pass.....but this isn't always the best means of getting about.....it often means that journey times are longer and that waiting around in cold bus shelters is what you want the older person to be subjected to.
Public transport in some areas is good, but then there are areas where public transport is run purely for a profit.....does not run at certain times of the day, does not run on Bank Holidays.......so yes these older people would be isolated, or could only travel the distance that they could walk.......this would suit some people, who it appears from this thread, want older folk to sit at home and do nothing more strenous than watch daytime TV.
I think it is very harsh to judge all older drivers by age alone....not everyone is the same.