You've been most helpful, so thanks again. Based on electoral rolls & what you've found, assuming he's the same person throughout, I've got John James Deighton living at:
1937 - 51 Gosset St, Bethnal Green (presumably still single)
1938 - 178 Bethnal Green Rd, Bethnal Gn (with Louisa & also Walter Henry Overy & Jane Elizabeth Overy, whom I know I'm related to)
1939 - 29 Allas Rd, Bethnal Green (with Frederick Thomas & Susan Humm, who tie in with what you've told me & would be his parents-in-law, but now no sign of poor Louisa).
Louisa (as Louisa Deighton)turns up from 1945-1952 at 15 Sewardstone Rd Bethnal Green, with various couples/singles so presumably alone, maybe divorced - or widowed since John James has by now disappeared off the radar).
The plot thickens. Bethnal Green Rd suffered huge bomb damage in the blitz (Sept '40) which might have something to do with it.
I'll see where I get to with Fredk & Susan Humm.