I agree that the lack of a father's middle name on a marriage cert is not enough to discount it, though the marriage cert will give Harold's age and occupation, his Dad's occupation and witnesses names may help to confirm it.
Deaths Q1 1972 Macclesfield
Clarke, Harold d.o.b. 12 Mar 1890
Harold Clarke, age 81, was buried at Macclesfield Cemetery 13 Jan 1972, address 10 Shaw St, plot Y grave no 16337
only 1 other burial in that grave which was
Sarah Ann Clarke, age 83, of 10 Shaw St., buried 24 Jul 1972
Deaths Q3 1972
Clarke , Sarah Ann d.o.b. 17 July 1889
1920 Electoral Register 10 Shaw St Macclesfield
Clarke, Harold Clarke, Sarah Ann
They appear every year at that address till 1931 (last year I have access to )
1919 Absent voters list 10 Shaw Street, Maclesfield
Clarke, Harold 165629 Sapper, R.E.
Free BMD search births, from 1913 to 1939
Surname Clarke, Mother’s maiden name Turner
Specify Maccclesfield District
Just 4 results : Winifred (1914), Elsie (1920), Margaret (1923), Dora (1929)
Brentnor boy mentioned an index entry for the 1939 register, I’d advise you to look at the image. Though I can’t post the details as its against Rootschat rules, I believe there was a family of 5 in that household, not one person on his own, and the image is quite likely to confirm a lot of the above info.
Do check all of this outcarefully, we can offer likely records/scenarios but its your family so only you can decide
Boo