My old neighbour was the head Gardiner for Piccadilly Gardens at the height of their beauty (he left eventually as they would never promote...he was too good at that particular job). This was probably in the 80's. He showed me some polaroids of his incredible work which coincided with the opening of the new Pizza Express. They ended up having copies of these photographs blown up and used as the interior on the walls (they may still be there...I haven't been since the opening). and gave him free pizza for a year...but he didn't really like pizza. He sadly died far too young a few years ago.
Definitely managed down towards the end but the fact they had to build on it just to so they had money to pay for that wall and gardens (both knackered) is a shocker (and indeed heads should've rolled).
I don't know but I suspect this new gardens is being managed down again and eventually a large scale redevelopment will take it's place (maybe even removing the Plaza/City Tower).
You only have to look at the fantastic job they've done with St.Peter's Square down the road (and the Albert Sq once rebuilt).
From Picc Station to Oldham Street, top of Market Street/High Street to Portland St (and that horrific Brittania hotel)...all absolutely horrid and stuck in Manchester's grimy past.