Hello I think in this case, in 1952, in England, a minor was a person under the age of 18. Te Age of Majority was 21 at that time, therefore a person under the age of 21 in 1952 required the consent of parents before they could marry. However, they could legally be married from the age of 16, (and therefore a minor)but parents consent was required.
In Scotland one could also be legally married at age 16 and a minor, and no consent was required from parents, and that is why there were elopements to Gretna Green.
If it says "minor" on your 1952 marriage certificate, it means that the person was 16years or above, but younger than 18 years old.
Trust this helps.