Lots to comment on here:
"I'm not sure it was such a sure fire hit when they transferred it."
I agree. Billy had the "machine" to steam roller it through any adversity, and it needed it. Other Olivier award-winning musicals that deal with the British working class experience haven't fared so well, and why should they? The whole singing socialist culture doesn't resonate in the US in the way that it does in the UK. Blood Brothers didn't repeat its incredible (and I mean that word in its most literal sense) West End success on Broadway. Spend, Spend, Spend never transferred and The Hired Man (arguably the best written of all four) took 24 years to transfer in an off-off-off-off-Broadway production that barely generated any attention.
"I will say that the staging of the "Solidarity" number...
...is brilliant at a near-Michael Bennett level."
Praise indeed coming from PJ.
That comment actually reminds me of a Q&A session Sondheim did in London a few years ago. I was initially uninterested in a Billy Elliot musical because I thought it would simply take 2.5 hours to say what At The Ballet said in 2.5 minutes: I expected it to be mawkish and sentimental and I knew I'd resent the politics. The minutes of the Q&A session I refer to quote Sondheim as saying
"Oh, Billy Elliot; the first 45 minutes - the staging - is one of the most exciting things I ever saw in my life, I think the first half of the first act is wonderful."
[Q&A Session with The Stephen Sondheim Society,
21st May 2006, Queen's Theatre, London.]
but my recollection of the event is that he actually said that the first 45 minutes were as good as anything he and Hal Prince did in the 1970s. That comment alone was enough to get me down to the Victoria Palace where I had my preconceived ideas blasted out of the water. And later when I read the minutes, I was surprised to read that they did not record what I thought I had heard.
Hmmmmmmm.