Diverse Range of Issues on Menu in Seven-Way UK Election Debate

Election debates
Britain's opposition Labour Party leader Ed Miliband (L), Deputy Prime Minister Nick Clegg (C) and Prime Minister David Cameron wait for Prince Charles at Buckingham Palace in central London November 21, 2013. Paul Rogers/Pool/REUTERS

Formerly fringe issues ranging from the UK leaving the European Union to scrapping the nuclear deterrent will take centre stage tonight in an unprecedented seven-way debate between Britain's party leaders in the run up to the general election next month.

After months of haggling over who would be invited to the debates, the leaders of the Conservatives, Labour, Liberal Democrats, United Kingdom Independence Party (UKIP), Greens, the Scottish National Party (SNP) and Plaid Cymru, the Welsh nationalist party, will all be present. The two-hour debate will take place on commercial channel ITV at 8pm.

The election is likely to be the closest fought in recent history, with the two main parties, Labour and the Conservatives, virtually tied whilst polling historically low shares of the vote. This combination is testing Britain's 'first past the post' voting system - renowned for returning strong governments - to the limit, and making it likely that whichever party gains the most seats in the election will have to do a deal with one or more of the minor parties in order to secure a majority.

How that two-party or multiparty coalition would work could depend on which parties are willing to work together on what could be a complicated compromise on a host of issues, many of which will be debated this evening.

One of the key issues up for debate will be Britain's continued membership of the European Union, and the leader of the UKIP, Nigel Farage, will make his case for Britain to leave. Conservative leader David Cameron has promised to put the issue to a public vote in an in/out referendum in 2017 if he stays on as prime minister, but said he will campaign to stay in the economic union. Labour and the Liberal Democrats meanwhile are adamant that staying in the EU is the best thing for the UK, with Labour leader Ed Miliband warning on Monday that a referendum on EU membership would harm British business.

Defence spending has been a controversial topic over recent weeks, with defence spending forecast to drop below the NATO target of 2% of GDP spend. A defence thinktank warned this could leave the British army with just 50,000 regulars enlisted. Added to that is the volatile issue of the UK's Trident nuclear missiles, which are due for renewal in the 2020s.

At an estimated £100 billion, parties such as the Greens and the SNP want Trident scrapped and the money spent elsewhere - the SNP are also keen to have the submarines carrying the missiles moved off the Scottish coast.

The SNP - while only holding six seats in the last election - could hold the balance of power after May 7, as the Guardian newspaper reports they could gain up to 56 out of 59 seats in Scotland, formerly a Labour heartland. The SNP was the driving force behind the campaign for Scottish independence, which was defeated in a close fought referendum, with 45% of Scots voting to leave the UK. Opposition parties are therefore warning that if Labour and the SNPs were to go into coalition, the country could be partly governed by a party that wants to split up the UK.

Government cuts to public spending are also a key battleground with the Conservatives wanting to cut deeper into the state, and point to Britain's growing economy and healthy employment figures as signs of their plan working. Labour haven't ruled out borrowing more money to sustain their public spending plans while the Liberal Democrats meanwhile claim to be somewhere in between the two. The Green Party, Plaid Cymru and the SNP are campaigning against austerity measures.

And another twist to the election could see Nick Clegg, the deputy prime minister, lose his seat if current polls are to be believed. A strong debater, Clegg was judged by many to have won the three-way leaders' debate before the last general election in 2010, when his party increased its share of the vote but lost five seats due to the first past the post system.

Cameron has already overcome one key hurdle in the election campaign - the avoidance of a head to head debate against Labour leader Miliband, in which he was seen to have much more to lose being the incumbent. He instead took part in a leaders' question and answer last week, where Cameron and Miliband were grilled by presenters but didn't face each other directly.