http://ukpollingreport.co.uk/guide/liberal-democrat-target-seatsAs T_i_B says, many are too solidly Labour or Tory to be realistic. Going down to the one Sheffield seat that might be in contention - Sheffield Central - that needs a swing from Labour of 8%, ir Labour lose 8% and Lib Dems gain 8% from last time - so the
notional 2005 result of Lab 46.6%, LD 30.6% becomes LD 38.6%, Lab 38.6%. That swing is roughly where the polls are now - Labour down from a national 35% to 27%, Lib Dems up from 22% to 30%.
But the swing against the Tories isn't so much - they're currently around 32% nationally, about the same as they got in 2005. So the Tory-Lib Dem swing is only about 4%.
From the target list, that would mean the Lib Dems gaining about 16 Tory seats, and 28 Labour seats. So that looks like 100-110 Lib Dem seats in total, when added to what they've already got.
Every week, PoliticsHome aggregates the week's YouGov polls to have enough to break it down by region. Here's the one from Monday, using data from April 11th-18th - ie mainly before the debate, but including a couple from after it:
http://www.politicshome.com/uk/article/8065/the_view_from_the_regions_19_april_10.htmlIt shows there is regional variation - the Tories were at 50% in the South East, 5% better than in 2005, compared to the Lib Dems being on 25% - exactly the same as 2005. However, that was compared to 52% and 19% from the week before, so the debate, even with only a third or so of the survey after it, seems to have had a significant effect. A lot of the Lib Dem target seats are in the South East, or other areas where the Tories are strong, so it will be interesting to see next week's regional breakdown, which will be post-1st debate (with a little post-2nd).