Benjidog and Tonga
I did return to Newcastle a few weeks ago and following your directions found the building which housed Nellist's until 1961.
It is now an office for an advertising agency and has been gentrified.
It used to have raggy old curtains and waist high weeds in the front garden.
I will post a picture I took in September 2007 of the building.
Again many thanks to Benjidog and Tonga.