I've found some photos now.
It was basically a rectangular kitchen unit, maybe 1500mm long, worktop, chopping board, prep sink where you would perhaps peel stuff and then lift it out to empty, bin under, implied storage under for oils, vinegars, wines, herbs, spices, knives, wiping cloths, pans (if it was me in real life I'd have a centrepull paper towel dispenser feeding through the worktop).
The front of it was made to blend in with whatever unit doors you had, and the back (where you stand) was open like a bar or shop counter for access to the stuff.
In real life you might also have put an ice bucket on the top and had glasses underneath; again, like a bar, maybe plates too.
Swivelling rubber-tired wheels with foot operated brake, set back from the edges to not show, 150mm for ease of rolling.
Front and sides dressed up with cornice and mouldings. It didn't have a real plinth, it stopped short of the floor so it could roll about without scraping. It must have had a braced timber frame because ordinary kitchen units are planted on the floor and fixed to the wall, so not expected to have any stresses of being trollied around.
Looking at the photos I see it enabled the rest of the kitchen to be fake. As it was a stage set it had to convey an impression rather than be totally practical.
You could of course make it to any design and size you wanted, but I think 1500mm is the maximum you could roll single-handed.
In my mind it was longer, perhaps I was thinking of a peninsular I had at a previous house. You could have a wider top and bar stools if you want. I think the idea was to bring the food prep area towards the living area, then push it back to the wall when no longer wanted. In real life it would be an island or peninsular that did not encroach into the room space when not in use. You could make it look like a sideboard if you wanted, and put your serving dishes, drinks, sorbets or puddings on it for when the staff were sent out.