Just to get a sense of when and where:
Marriage, September qtr 1940
Hammersmith Registration District vol 1a, page 863
Robertshaw, Margaret
Dwyer, James
The Marriage Certificate will give father's names - essential for tracing any further.
Probable birth for Keith Hadaway:
June qtr 1945
Cambridge Registration District vol 3b, page 864
Hadaway, Keith P Mother's maiden name: Field
Other possibility:
September qtr 1942
Nelson Registration District vol 8e, page 278
Hadaway, Keith Mother's maiden name: Heseltine