I think the CSA (and Cubana) Britannias used to come to the UK for major checks, initially to Filton for as long as Bristol/BAC did them, then at Monarch at Luton. If either company's aircraft was off line for a check they would borrow from the other.
Cabin service was very good with free Czech beer offered to all just after take off
CSA were still very good with that 10 years ago, before it all fell away for them. I used to use them on London-Prague-St Petersburg as a notably cheaper alternative to the direct flight; they always came in and out of LED at the same time as BA and parked on the next stand. Even then, during the stopover there was still a large somewhat socialist-style cafeteria in Prague terminal, rather like a factory canteen but with great Czech food and drink. A week before Christmas CSA gave out nice chocolate Santas on the catering trays.