Image copyright PA Image caption These seats were last fought at the same as the 2015 election - a good night for the Tories

This year sees the biggest set of local elections in England's four-year electoral cycle.

There are more than 8,400 seats up for grabs plus a further 462 in Northern Ireland. That's almost twice as many as last year.

There are no elections in Scotland and Wales or in a few parts of England - including London, Birmingham and Cornwall.

Most of the seats being contested were last fought in 2015 on the same day as the general election where David Cameron won a small majority for the Conservative Party - their first for 23 years.

That was also a very good day for Tories in council elections. The party made more than 500 gains - an impressive result for a governing party.

It was also a good election for UKIP, whilst Labour and the Liberal Democrats suffered losses. This means that most of the seats this year are currently Conservative held.

Seats being defended by each party:

Conservatives: 4,901

Labour: 2,105

Lib Dem: 647

UKIP: 176

Green Party: 71

Ind/Oth: 518

With such a large set of elections, the scope for big changes is increased.

In this case, that's especially true for the Conservatives who are starting from a high point whilst their national poll ratings are pretty dire.

However, the range of other parties which voters will be able to choose between is limited as there are no Brexit Party or Change UK candidates.

What I'll be looking out for at 03.00 in the morning

By John Curtice, Professor of Politics at Strathclyde University

The absence of the Brexit Party from these elections could be crucial and could explain if the Conservatives do somewhat better than their relatively dire position in the national opinion polls.

As well, UKIP are only fighting one in six of the seats.

One of things we will be poring over at 03.00 BST on Friday morning is whether or not there is a difference in the Conservative performance in those wards where UKIP are standing and those where they are not.

The truth is for most Leave voters unhappy with the Conservative government over Brexit they have nowhere to go in most places in these local elections.

Do they turn out and hold their noses and vote for the Conservatives, which is what Theresa May has to hope, or do they stay at home?

And, if it the latter, will turnout fall away in those places where there is no Eurosceptic candidate?

On the other side of the Brexit argument, the Lib Dems could well do with a relatively good performance because they don't have the challenge of Change UK, which is not on the ballot paper.

Change UK are, frankly, fishing in exactly the same waters as the Liberal Democrats. They are basically going for socially liberal, pro-Remain people who are relatively comfortable about immigration. It is very much the same market.

The Lib Dems are the past masters of "pavement politics". But look at the Lib Dems position in the national opinion polls and it is exactly the same as 2015 when these seats were last fought.

The truth is the Lib Dems are bound to make some gains simply because the party's performance in 2015 was their worst ever in local elections.

One of the things we will be able to do is not only compare the position with 2015 but compare the position with last year, when they were running at about 16% in local elections.

Can they do better than that and begin to win over the Remain vote? Because if they can't do it now, they may well be struggling in three weeks when European elections take place.