Electoral registers (on ancestry)
I didn't see John and Florence Armstrong on those Middlesbrough electoral registers.
There is a pair with the same names, but they are not the right ones at all (appearing on the wrong dates!)
An idea...what if they were in Eston? And Florence met Thomas Nesbitt there?
Of the few John Armstongs in Eston in 1939, one may be a possibilty.
At 5 West Street.
Margaret Armstrong, born 1870, Widowed
Gweneth M Armstrong (later Chinery), born 1906, Single
Richard J Armstrong, born ??, Single
John Armstrong, born 16 Apr 1905,
Married, Stocktaker Section Mill ??