Hi Discorde,
As sure as I can be with the passage of time- it was only very occasionally that a crew did this, but I'm fairly certain.
I am definite that Swissair (cargo) DC9's did FL350 from Manchester to Glasgow (every time- I think- they operated that short-lived flight), but that is of course a longer distance.
When once on the flightdeck of Shuttle Trident 2 (LHR-GLA), the Captain said they could make 6000ft RoD easily - photo of said flight passing FL330 at 3000ft RoD (G-AVFE 25th May '82)...
Apologies for poor image quality.
For nostalgia, here's three Tridents and a Dan Air 748 at Glasgow (poss also a BA Budgie beyond the Tridents)...
