Car parking on the 'pavement' outside Forest Lodge and 117 Dartmouth Road, whilst not being ideal, is historic (47 years that I've been around FH!), hence, in my opinion, whoever wants to change it (Lewisham/TFL?) should have sought to do so through proper consultation with the beneficiaries and the legal process long before getting the roadworkers in.
If I lived there and had become reliant on a parking space - or if I lived in Thorpewood or Sydenham Park - and all of a sudden bollards were put in willy-nilly, as per the scheduled works, I'd keep smashing them down until someone got the message.
I hope that after all these years of Lewisham's acceptance of the status quo they will struggle to put a strong enough legal case together to affect the current adopted use of this land. But this might depend upon some residents who've had continuous use of the parking spaces for the statutory period of 12(?) years.
With safety in mind, obviously, as with anyone anywhere who drives across a footpath to access a parking space in front of their property - be that a driveway or a crossover - there is a responsibility to do it with the utmost care to pedestrians and other motorists so, unless there is a poor accident record, that shouldn't be held as a reason why this can't continue to happen in this particular location.