http://www.electoralcalculus.co.uk/homepage.html
They don't show the previous update, so here it it ::
CON....263........now.....251
LAB.....302........now.....316
LIB......16..........now.....19
UKIP.....0...........now.....0
NAT......50.........now.....45
MIN......19..........now.....19
So the difference in predicted seats for May 205 are CON = 12 less, LAB = 14 more, and NAT 5 less. So, still no seats predicted for UKIP.
LAB now has a 42% of an over all majority, up from 34%, and CON now has a 8% chance, down from 12%. Bear in mind that was based on Polls 07/11 to 28/11, so would include the latest UKIP win in Rochester.
I will update again at the end of December.