I think the big difference that nobody has brought up is that the NDP is a party of the edge of the spectrum (in so far as elected members) just as is the Conservatives. The Liberal Dems are the middle party in England as the Liberals are here.The process for a centre party to come back from the dead in a system that has polarized is different than trying to get definition through polarization in the first place.
I agree with your analysis Sean. Again the parallels between the 1991 BC election and the current UK election are uncanny.
The 1991 moribund BC Libs only had one week from their own "Clegg" moment until election day and garnered 33.25% (from 6.74% the previous election). Again, NDP strategists later confirmed that had the BC Libs had an extra week until election day in 1991 they would have won - Believe it or not.
The Lib Dems have that extra week or two and such a juggernaut is difficult to stop. Using the 1991 BC election as a template, I expect the Lib Dems to be polling in the 35%+ range by this weekend. We will see if that rings true.