London Set To Be Key Election Battleground

Sadiq Khan is expected to make history, with the son of an immigrant bus driver on course to become the first Muslim mayor of a major western city.

As Londoners took to the polls on Thursday, senior Tories were privately admitting their man Zac Goldsmith was on course to lose to the Labour candidate – ending the Conservatives' two-term reign at City Hall under Boris Johnson.

While Mr Johnson edged to victory over Ken Livingstone in 2012, Mr Goldsmith has faced an uphill battle in the Labour-dominated capital, with Mr Khan extending his lead over the Etonian eco-warrior as the year-long contest has gone on.

The bookies' odds tell the story: William Hill is offering odds of 1-12 on Mr Khan, against 6-1 for Mr Goldsmith.

But that doesn't mean that upsets are not on the cards when it comes to the London assembly elections where 25 seats are up for grabs.

Only three seats have changed hands since the assembly was created in 2000 - but this year is looking decidedly more interesting.

Barnet and Camden is one to watch.

With a big Jewish population, this Labour-held seat could become a lightning rod for voter anger over allegations of anti-Semitism in the Labour party – and both sides are watching closely to see what will happen to Andrew Dismore’s 21,299 majority.

"It will hurt," said one figure in Mr Khan's camp. "It hurts the Labour brand and we are fighting under a Labour brand."

Havering and Redbridge: Once a Conservative stronghold, in 2012 this northeast outer London borough became the second most marginal seat in the assembly, with deputy mayor Roger Evans turning in a 3,939 majority.

Labour are targeting this seat. But watch too for a big spike in the UKIP vote in this seat.

Ealing and Hillingdon: The Tories' top target: Onkhar Sahota achieved a 13.4% swing in 2012, unseating the Conservative Richard Barnes.

Labour has a majority of just 3,110. The Tories will need a 3.4% swing to win it back.

Sutton and Croydon: A hotly contested battle ground in the south of London. The Tories lost control of the council here in 2014 but managed to cling onto Croydon Central in the general election (Gavin Barwell held his seat with just a 165 majority).

Labour need just a 2.5% swing to take this seat. Where the Liberal Democrat vote goes (the party often gets 30,000 votes in the constituency) could well decide this tight race.

Merton and Wandsworth: A Labour target seat in the southwest of London.

This seat has been Tory controlled since the assembly was formed in 2000 but that Conservative’s majority is being whittled back and Labour now need just a 2.5% swing to finally topple its rivals.

:: Watch Decision Time for full coverage on all of Thursday's elections on Sky News throughout the night.