I saw the show on Monday evening - the first musical I have ever been to see. I thought it was very good.
The sparse set composed of ladders and packing cases works well, with Floyd Collins spending most of the show "trapped" by one foot under the bottom rung of a ladder. Cavers who like to crawl through chairs at the end of an evenings drinking will find the acrobatics of some of the cast familiar.
The plot is (understandably) a terse version of reality, and the cast is not huge with some individuals conflated or omitted; but it works well. I found the music very pleasant, although sometimes it drowns out the singing - the drums in particular were too loud. The acoustics of the vault do the production no favours and this was the only shortcoming.
Best of all - the theatre in a railway arch below London Bridge station smells of cave!
All in all, well worth seeing.
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