Things you could do once, but can't now

Obvious one here(and this is thanks to former mayor Ken Livingstone) you can no longer go to Trafalgar Square and feed the pigeons. It used to be fun holding out a small pot of food(which was 10p bag and not bloody tuppence like in Mary Poppins) and then get surounded by pigeons cooing and looking for food. Okay I know they were a bit of a health hazard later, but London was unique in this activity and us kids loved it. Livngstone called them 'flying rats' and eventually they were phased out.

I'm not sure if this counts but one of my first jobs I had when I was at school was starting at 5am doing a milk round with one of my mates and a boss (driver) in one of those really old milk floats with the open back and sides and a roof. When we were driving from estate to estate delivering, me and my mate to save getting in and out of the van, would hang onto the back on either side as we were driving along, bloody crazy now I think of it but no one battered an eye lid back then.
Going through the country lanes was a bit of a nightmare, getting caught up in the brambles in some of the hedges but great fun and at that age we loved it!!
Even going through our town centre people would just wave and smile and we'd be laughing our heads off!!! Definitely wouldn't get away with that now I think!!

Are the closed pubs given listed status or not?

Security has stopped things that you could do. I've been up the BT Tower in London and been on the roof top platform at Manchester airport.
But not any more due to security issues.

Go into London for less than a tenner - now you need a bloody bank loan before you start

Getting your milk delivered to your doorstep every morning.

Taking your pop bottle empties back to the shop and getting money for them.

Buying a bag of chips for 5p. Yes I remember being able to do that. Would have been 1973/74 time..

Walking onto the tarmac to get to the steps up to an aircraft for your holiday-later they introduced the walk-through tunnel straight onto the plane.

Going up to the top of the then Post Office Tower(BT Tower) to the revolving restaurant -this was closed off to the public when the IRA threat reared its ugly head and never reopened -it was a few years ago for its 50th anniversary and people entered a lottery to win the chance to dine up there, whilst it revolved slowly round.

I WAS told it as he best view of London, I think now you'd have to go up to the tp of the Shard to get anything more spectacular.