Edmonson card tickets stamped with a filthy great "W." For those younger members who wouldn'y know about this, it's all in the caption
I - incorrectly as it turned out - guessed those were for "Workmen's trains" - early morning trains into London before the peak at lower fares. Some mention of them at
https://blog.railwaymuseum.org.uk/fares-fare/ - which tells me they were renamed to be politically correct as "early morning returns" and then abolished in 1961. I find myself wondering if there's a case for off peak (or super off peak) to be valid for trains scheduled to arrive in London before 07:30 or before 07:00.
Workmen’s tickets were printed as workmen’s tickets anyway.
In the olden days of racks of Edmonson card tickets and a date stamp, all tickets in the rack had a fixed price, much as they do today (ie. there would be singles, ordinary returns and day returns between A and B) The only tickets that were not fixed price were blank card and paper tickets and these, if I remember correctly, were entered into a ledger showing the destination and the price they were sold for. I would imagine that Heritage railways do much the same thing today, albeit with a bit of computerisation thrown in for good measure.
At the end of the day the booking clerk would balance the cash by noting how many of each ticket were sold, the sum of the blank card and paper ticket sales, and check that that was the amount of cash in the till.
It will be seen that by this system, stamping what would otherwise be a fixed price ticket, with a W or indeed anything else to indicate that it had been sold at a discoutned price, would have complicated the accounting process and would also have theoretically been open to abuse.
Certain trains, especially in the Welsh Valleys, actually appeared in the timetable as “workmen’s trains” until the concept was discontinued. Presumably from then on “workmen” either paid for a day return or another suitably-defined cheaper ticket from the ticket rack.