(13 Apr 2020, 10:40 am)ifm001 wrote No date from the pic 
But attached.  What year did 7021 get introduced?

The dvla don't seem to have details available for 7021.
However, the picture of SJP gives a clue to the dates. 
The wooden West stand was demolished in 86ish, following on the Bradford City fire in May 85. The Milburn Stand would have been completed a year later, dating this photo between 84 and 86.