Clearly he went on a good few years too long (and I've no doubt that there'll be a few of you who'll argue he should never have started to begin with!), but was there any point at which the blue-eyed version of Shirley could have hung up his boots without being held responsible for the decline of British wrestling?
The 1981 Wembley bout with Haystacks (despite its rubbish, flower-strewn finale) seems to have been the high watermark of his popularity - everything after that looks like diminishing returns.
Perhaps following his tag match partnered with Jim Moser .v. Haystacks and Bromley when he was due to step away from wrestling to present a Saturday morning ITV children's show with Isla St.Clair. By then his solo contests were virtually non existent and his tag routine was predictable.
By now gone were international tag opponents, and without sounding too unkind in came huge ungainly men with little experience, who no one had ever heard of or seen before. In 1979 when Shirley defeated Mighty John Quinn (a favourite of mine) i was 13, i thought it a was tremendous victory. Only to be massively deflated by Daddy's showdown with Haystacks two years later.
A wrestling website called something like "britishwrestlingarchive" collated Shirley's Big Daddy era contests which suggested he faced virtually every British heavyweight around during that era in solo contests up until 1978 when his tag career took off. During his solo bouts he actually lost quite a few contests as both a heel and a baby face, including a British Heavyweight tile eliminator against Tony St. Clair, along with wins via disqualifications against Mal Kirk, Wild Angus & Haystacks.
Personally i would have liked to have seen Shirley continue his solo contests alongside the tag matches, perhaps 50/50, as the single bouts would have made him appear more vulnerable than his one man wrecking ball tag matches in the 1980s. There's no doubt that Shirley was the reason many came to the halls to watch wrestling, but following his bouts of illness he should have been allowed to retire. By the mid to late 1980's age and illness were taking there toll, Shirley looked an old man, and he made for uncomfortable viewing. He'd shrank in height, size and weight. Shirley had always looked bigger than the great Mal Kirk. By now he looked smaller and greatly aged.
Yes i think Shirley should have retired following his win over Bill Bromley & Giant Haystacks.