As far as Britain is concerned, I first became aware of large numbers roosting at various south London sites in the early 1980s. There was one cemetery that regularly held numbers of 1,000 to 2,000. Without delving into my copies of the annual London Bird Report going back to 1980, a quick internet search brought up the LBR for 2014 where a peak roost of 3,900 at Mitcham Common was recorded.
I think Mr Reddy can only expect ever-increasing numbers! This is a highly successful and adaptable species, and like other parrots, pretty intelligent.
Edit: it's important to note that this is now considered an invasive species and a cause for some concern. I've posted this RSPB link before.