What you looking for, Dean, does not exist in Britain at the moment.....a city centre track. Earlier you mentioned Workington, great track, so is I believe Redcar and Scunthorpe, throw in Glasgow and that's your nearest to Newcastle (that have a reputation of being race tracks). Could argue Sheffield is close to city centre...maybe 1 mile away, after that struggling for good race tracks until get to Poole. Iffy would be the likes of Ipswich, Oxford and Leicester, Kings Lynn may be viable...but that's it IMO.
Belle Vue is not just a good race track...it's brilliant. After last night GP I was on YouTube and watched some heats from the BLRC, Peter Collins gate 1, Ivan Mauger gate 4, two other very capable riders. Collins had to come from the back (not a shock) to pass Mauger.....it was just like watching last night's SGP... passing line so similar. Not surprising since Mort designed the NSS, and he took into account not only Hyde Road but also some Euro tracks..I believe Torun was one of them.
Point is...there is nothing else available in Britain to match the NSS....it just needs tweaking is some areas, like food and drink. Surprised no one mentioned toilet facilities. Back on 2016, for the world team/pairs, facilities for the 3rd/4th bend were lacking.