Can the Gov't survive - a seat by seat analysis:

Seeing as the rest of parliament is basically to the left of Labour with the exception of the DUP - Well Con + DUP + LD + UKIP needs to = 323 for Dave to hang onto power.

Even at 323 it is highly dubious that the LDs don't switch sides, but we can regard it as an absolute minima.

Con/LD; SNP/Lab not important for this analysis:

LD losses to Labour according to Election forecast.

Bradford East
Brent Central
Manchester, Withington
Norwich South
Redcar
Burnley
Cardiff Central
Hornsey and Wood Green
Leeds North West
Bristol West

(10 losses to Lab)

Orkney is the 1 LD Hold against SNP (9 losses) - BRS switches LD to CON on the model.

Con losses to Lab.

6 London (Hendon, Brentford Isleworth, Enfield North, Ealing Central Acton, Croydon Central)
8 NW (Lancaster, Fleetwood, Chester, Bury North, Wirral West, Morecambe, Warrington South)
3 East (Waveney, Bedford, Ipswich)
2 Yorkshire Humber (Dewsbury, Keighley)
3 West Mids (Wolves SW, North Warks, Nuneaton)
2 SW (Plymouth, Stroud)
2 SE (Hastings, Hove)
6 East Mids (Erewash, Amber Valley, Sherwood, Lincoln, Amber Valley, Broxtowe)

The current potential centre-right coalition/confidence & supply arrangement is as follows Lib Dem total is 56, Conservatives 302, UKIP 2, DUP 8.

So  368 'forces of the centre/centre-right'

Subbing the Lab losses yields  358
The 9 SNP losses gives 349.

And then the  32 Conservatives gives 313..

To begin to have a prayer of staying as PM, 10 Holds are needed from this lot, and also crucially no losses 'off the list'.

Scotland looks to be a fair reflection, as even though some argue East Dunbartonshire might stay Lib Dem (Or even Thurso), DCT and BRS could both well go to the SNP... particularly BRS. Dumfries & Galloway could even be a CON gain. Though this is unlikely. Nine losses to the SNP looks about right to me.

With the Lab gains from LD 

Brent Central
Manchester, Withington
Norwich South
Redcar
Burnley
Cardiff Central
Bristol West

Are all surely dead. If Bristol West doesn't go red, it is going Green and that is of no use to Dave whatsoever.

Hornsey and Wood Green looks fairly dead too, and there are some arguments that Ward PV may hold Bradford East.

Leeds North West is odds against, but then again Birmingham Yardley and Sheffield Hallam could be brought into play.

Eight is a working minimum here.

Which gives 351 seats.

So 28 is the absolute and complete minimum no of seats Dave needs to stop shipping...

The Labour seat total is almost immaterial, it is all about the above group hitting 323

Even then it may not be enough.