For those comparing with BR, in 1993, at the peak of InterCity under Chris Green, the first train from London to Sheffield was the 0700. This was an ‘InterCity Shuttle’ with trolley service of snacks and hot drinks at seat. There was a buffet, no doubt with the ubiquitous burger. Only the 0800 to Sheffield had a restaurant service at that time of day. Later northbound restaurant services were back workings of early Up trains.
Well it was in the 1990s, and likely on the 0700, that I used to do St Pancras to Derby quite a bit, and it was BR full breakfast. On one occasion I joined at a table for four someone already seated there who seemed to be known to the crew. Off we set, and they came over with a plate of toast, announcing it as "just for him", followed by a fully plated breakfast, again just his, ahead of the normal silver service. He must have noticed I was looking at the passing stations because he asked "was that St Albans", to which I replied "No, Harpenden", whereupon he sped up in his sausage consumption. Brakes on, the steward appeared with his bill, he slammed £15 into the stewards hand, who then pleasantly opened the door for him as we drew to a stand at Luton. Gone.
On another occasion there were two American businessmen across the aisle, quite unused to train travel and seemingly booked into their First Class seats by their UK office. Doubtless only used to plane travel, they exchanged constant comments about how impressed they were with the BR breakfast quantity and quality - but were then quite nonplussed at the end to be presented with a bill for it. As I said, only used to plane travel.