A correction - it was Mary E Quinn (double n) born 19/1/1929 and living at 57 Rothwell Street, Bolton, Lancashire with John W Yates and May E Quinn - parent, together with Norman 28/11/1927 and John R 7/7/1931. John and May were married, but he was obviously not the father of the three children.
Wonder if Ethel could have dropped her first name?
Carole got in just ahead of my posting - I agree, the Baird 2nd wedding cert is an important document to get.
With regard to the 1939 entry Nookie posted, yes the year of birth is different
Also, looking at the 1939 entry, I'm not convinced the children's surnames are Quinn - I think the enumerator has left all the surname entries blank (as he/she has further down the page) to indicate they are all Yates.
Added, yes - there are matching birth refs for all three children as YATES with MMN Pasquil(l)
Further added: and May E Yates married Leonard Quinn in 1953 in Bolton.
So we can def rule out that 1939 Register entry.