I have in front of me my Student Pilot Licence n. 73XX94 issued on 31 March 1966. It is valid for 2 years from the application date, until 21 March 1968. It has a medical certificate embedded in it with a 1967 date, presumably a renewal, (which specifies I wear my glasses).
The privileges of the licence are stated as me being "entitled to fly as pilot in command of an aircraft for the purpose of becoming qualified for the grant or renewal of a pilot's licence." It specifically excludes being PiC of an aircraft in which a person is carried. It also restricts me to the UK, Channel Islands or Isle of Man, and also only to flights carried out with the specific authorisation of a licence holder who is also a flying instructor.
I recall that this had to be applied for, and received, before you could be sent solo in the 60s. Presumably someone in the Ministry of Aviation took a hard look at the relevance of this practice some time later and binned it, replacing it with the far more sensible hurdles of the medical (and passing the Air Law exam, IIRC in 1991?) before going solo.