(Thanks to Media Boy for the information in a comment to a previous post):
The following area will join NGTV (and be ready for additional HD channels on April 1) this week -By my count that leaves a couple of dozen still to go. At this rate they should be done by mid-May, but I'm assuming there that each area involves the same amount of work. Upgrades are mid-week (Tues-Thurs) but there may be a slowdown either side of Easter. Dunno. There's now a dedicated Cable Forum Thread on the NGTV upgrade.
Manchester (Stretford, Withington, Rochdale, Oldham.)
Manchester (Birkenhead, Bromborough, Salford, Wardley.)
Incidentally, there's a placeholder for ITV1 HD for all area in England and Wales now on channel 113.