With exactly half a year left until polling day, it’s time for my latest prediction of the election result.

As usual I’m forecasting a hung parliament. But for the first time I’m saying there will be multiple gains by parties other than just Labour and the Conservatives. And for the first time I’ve split apart the “others” category to allow a fourth party to take its place in the pie chart:

I’m a naturally cautious person, so I’m not – as yet – predicting the SNP to do what two opinion polls suggested recently and take around 40 seats from Labour. I’m equally hesitant about Ukip’s chances, and have limited them, for now, to Douglas Carswell retaining his seat in Clacton. But both scenarios may well have changed by this time next month.

Labour’s total of 299 is up 41 on its result in 2010. It includes Corby, which the party won in a by-election in 2012, but doesn’t include Bradford West, which it lost to George Galloway in the same year.

The Tories’ total of 278 is down 28 on their result in 2010. This figure doesn’t include the seat of the Speaker, Tory MP John Bercow.

The Liberal Democrats are actually on the same total I gave them last month, but as you’ll see below, their losses are now split between three parties. I’m aware I’m continue to remain very generous to the Lib Dems, particularly in light of their continuing wretched performance in the opinion polls.

The SNP are up eight on the six seats they won in 2010. I’m giving them three gains from the Lib Dems and five from Labour: not at all in line with those headline-grabbing polls of last week, but I’m waiting to see more evidence than just two surveys before extending their tally any further.

Even though my latest forecast revises Labour’s total down 11 seats from the 310 I gave the party in October, Ed Miliband could still end up prime minister thanks to a Labour-Lib Dem coalition. The combined total of such an arrangement would be 334: eight above the number needed for an absolute majority in parliament. A Tory-Lib Dem coalition would total 313: 13 below the target.

Here’s how I calculated this month’s prediction:

Labour’s 45 gains

From the Lib Dems: Norwich South, Bradford East, Brent Central, Burnley, Manchester Withington, Dunbartonshire East, Birmingham Yardley, Hornsey & Wood Green, Cardiff Central, Redcar and Cambridge (total = 11)

From the Tories: Warwickshire North, Hendon, Cardiff North, Sherwood, Stockton South, Lancaster & Fleetwood, Broxtowe, Amber Valley, Wolverhampton South West, Waveney, Carlisle, Morecambe & Lunesdale, Weaver Vale, Lincoln, Plymouth Sutton & Devonport, Stroud, Brighton Kemptown, Bedford, Dewsbury, Warrington South, Pudsey, Enfield North, Hove, Northampton North, Brentford & Isleworth, Halesowen & Rowley Regis, Nuneaton, Ipswich, Blackpool North & Cleveleys, Croydon Central, Harrow East, Ealing Central & Acton, Norwich North and Dudley South (total = 34).

The Tories’ eight gains:

From the Lib Dems: Solihull, Dorset Mid & Poole North, Wells, St Austell & Newquay, Somerton & Frome, Chippenham, Berwick-upon-Tweed and Cornwall North.

The SNP’s eight gains:

From the Lib Dems: Gordon, Argyll & Bute and Caithness, Sutherland & Easter Ross (total = 3).

From Labour: Ochil & South Perthshire, Inverclyde, Dundee West, Falkirk and Aberdeen North (total = 5).