Family had business connections with a travel organiser called Fred Tjolle, a Belgian emigrant who had joined the railway in WW2 at Bristol St Philips Marsh, rising to driver, (and ASLEF branch secretary) who then left and started a travel company around late 1950s-early 1960s, which did package holidays to Belgium, marketed particularly at Bristol/South Wales railway staff and families, who got the rail travel part of the holiday, to Dover and thence the ship to Ostend, free. Took thousands of rail staff. Described in this article by the organisers' own son:
https://valerex.wordpress.com/2009/02/03/my-love-affair-with-tourism-you-lucky-people/
Meanwhile I had moved on to university at Edinburgh in the 1970s where a course colleague, son of a senior manager based in London, got the family first class facilities, and would come to/fro in the sleeper from Kings Cross. It was there I heard of the tickets being applied for as Penzance to Wick, which made it effectively valid on all services.
But more so at Edinburgh, what I did notice was the number of rail management staff working in both Glasgow and Edinburgh who lived in the opposite city, and commuted on the Class 27 Push-Pull. This had one of the six coaches first class. Now Scottish regular passengers are a sensible set, and nobody I ever knew, even seniors in the business world, ever paid for first class tickets on internal Scottish services, so the first class coach was generally empty stock - apart from at peak periods, when it formed a sort of private club for the managerial grades, who travelled in isolation whilst at the same time there were standees in all coaches of the rest of the train. Which I always felt was a bit disappointing.