IIRC the money (5 x £1) came in a sort of rigid plastic case. Remarkably, my Dad, who has never exactly been an early adopter of modern technology (think that’s polite enough!) used that service very early. I should imagine it was very quickly superseded by something more flexible and less wasteful.
I have a memory of the 1983 general election of trekking out on the bus from Birmingham into the wastes of the Black Country to hear leader of the opposition Michael Foot give a speech just before polling day. It was in something like a wooden Scout hut; there were a few TV cameras but no great security as I recall. We were just able to walk in off the street, there were no tickets or advance bookings.
After the event, we repaired to the Crooked House pub (somewhere else that is no longer functioning) for a few pints. Owing to my mate misreading the bus timetable, we thought we'd missed the last bus back to Birmingham (we hadn't, but we didn't know that at the time) so we walked the 12 miles home.
Recalling the episode years - decades - later, we asked ourselves: 'Why didn't we get a taxi?' (We were students, but not completely poverty-stricken; one of us was on secondment from London Transport and still getting a salary.) The answer, we eventually realised, was that we didn't have any cash on us. There were no ATMs in those days, minicab firms probably wouldn't accept cheques, so without folding readies, you were stuck.
I too remember a very primitive bank card - a piece of plastic with holes punched into it that you fed into a slot in a machine on the one and only bank in Birmingham that had one. After a few mechanical rumblings and creakings, it spat out a tenner (you had no choice as to the amount) and a few days later you got the card back in the post.