In message ,
Muddymike writes
On 05/10/2020 11:00, Graeme wrote:

I imagined cutting into the lid against the existing rim, such that
the lid would come out leaving the rim in place.

Then your left with a flat steel disk that cant be used as a lid.

You're right of course, but the plan is to chuck it in the greenhouse,
at least over winter, which will at least keep it dry. The good news is
that the drum came from a local confectionery business, and they have a
regular supply of drums, and are always happy to give away the empties.
I could grab a second drum to replace the first, or to just cut the top
off to use as a lid, as you suggested.
--
Graeme