(18 Apr 2015, 12:42 pm)Malarkey wrote What were the reasons behind Pedestrianising Northumberland Street, and which year did this take place, looking at that Photo I dont think we would ever see it reopen to traffic.

Probably to move traffic away from the city centre/shopping area.

Up until the mid/late 90's, the very top (onto Northumberland Road) was still open for buses.
The remaining section still had restricted access and a small road going down the middle for a long time. Possibly into the early 90's.

Edit: http://www.skyscrapercity.com/showthread.php?t=982536&page=113 found this, with images of the changes and the small road that wound its way down.