London Assembly Projection, April 2016

So: YouGov have finally released a poll of London Assembly voting intentions, which I was beginning to think they'd never do.

A Universal Swing projection of the Assembly result based on the YouGov poll.

I warned a few weeks ago that Labour should expect a slight decline in their London Assembly results, as their 2012 score was a high point. Instead, they've blown past it. In 2012, Labour won 41% of the List vote; they're now polling at 45%. The Tories have dropped 3 points and the Greens 2 points, while both UKIP and the Lib Dems have improved solidly on their 2012 result.

I used a 'universal swing' seat calculator that I've constructed, and put the constituency and regional poll results through it.

If this poll was repeated on May 5th, Labour would win 12 seats on the London Assembly (no change), the Conservatives 8 (-1), UKIP 2 (+2), the Lib Dems 2 (no change) and the Greens just 1 - their Mayoral candidate Sian Berry (-1).

The breakdown

The 'no change' for Labour is a consequence of the proportional "Additional Member" system used in London. In the "first-past-the-post" section of the ballot, Labour would pick up 2 Assembly seats from the Conservatives (Croydon & Sutton and Havering & Redbridge) and would come within 0.2% of a third (Merton & Wandsworth).

The YouGov poll shows the Constituency voting intention as:

LABOUR 46% (+4%)
CONSERVATIVE 30% (-3%)
UKIP 9% (+5%)
LIBERAL DEMOCRAT 9% (-)
GREEN PARTY 6% (-3%)
OTHERS 0% (-3%)

In total, the constituency seat breakdown would be:

LABOUR 10 seats (+2)
CONSERVATIVE  4 seats (-2)

Under the D'hondt proportional allocation system, the remaining seats would be allocated to ensure that parties' seats reflect their overall share of the Party List (regional) vote. The List vote is as follows in the YouGov poll:

LABOUR 45% (+4%)
CONSERVATIVE 29% (-3%)
UKIP 9% (+4%)
LIBERAL DEMOCRAT 8% (+1%)
GREEN PARTY 7% (-2%)
OTHERS 2% (-5%)

The Tories would thus grab 4 List seats, Labour 2, UKIP 2, the Lib Dems 2 and the Greens 1.