Well there we have it. Jeremy Corbyn has defied all expectations, rising from rank outsider to become leader of the Labour Party. The next five years of British politics will be very interesting indeed. Any Labour MP leading the party would have a difficult task ahead; bringing the party back from electoral wipeout in Scotland and boundary changes in England to gain a 10 point upswing and win in 2020. But let’s put aside the challenges for today, and focus on the positives.

So if you’ve got a stake in the fortunes of the left, here are five reasons to be cheerful:

1. There will finally be a mainstream political figure who will oppose cuts to public services

Since the Coalition government took office in 2010, there has been an explosion of grassroots opposition to spending cuts from UK Uncut to The People’s Assembly. There have also been a substantial number of economic experts arguing that cutting public spending is a bad way of reducing the deficit, from Nobel Prize winning economist Paul Krugman to the IMF. But these sentiments have not managed to find their way into mainstream politics, not least because Labour’s response to Conservative arguments has been rather tepid. Under Ed Miliband, the Labour Party seemed to accept the overarching premise of austerity and focused on quibbling with detail. This created a consensus amongst the three mainstream parties that cuts were the only option. But the media will be required to give Jeremy Corbyn a regular platform in his role as leader, and perhaps the public will finally be able to hear the arguments for better, more prosperous fiscal policy.

2. A 50% female shadow cabinet

It’s a scandal that only 22 per cent of people in public life are women. It means women have less control over the decisions that affect them, and leaves girls with fewer role models to look up to. So it’s great that Corbyn will aim to ensure that half of the people in his Shadow Cabinet will be women – a political first. Finally there might be the critical mass of women in parliament to achieve a cultural change, and to cap it all off Corbyn has consistently voted against policies which disproportionately affect women, like cuts to welfare and a stricter asylum system.

3. Labour members will have a better chance of influencing policy

At hustings organised by The Guardian, Corbyn said: "I don’t think we can go on having policy made by the leader, shadow cabinet, or parliamentary Labour party. It’s got to go much wider. Party members need to be more enfranchised. Whoever is elected will have a mandate from a large membership." So there you go. Tired of shouting at the TV when politicians do things you disagree with? The Labour Party under Jeremy Corbyn might just listen to you.

4. The left could become an active force in communities across the country

It’s estimated that 600,000 people are now registered supporters or members of the Labour Party. Corbyn has been addressing packed-out rallies up and down the country for months. In Llandudno, 1 in every 40 residents went to hear Jeremy Corbyn speak, and as someone who hails from that part of the world, I can confirm – that is remarkable. What if the left put this energy to good use? What if just half the people who have attended Corbyn rallies started trying to organise their communities? That could achieve real democratic change at a local level. Thanks to Corbynmania, we now know people up and down the country will give up their evenings and weekends for politics. The left must do something constructive with that knowledge.

5. Tony Blair is not the messiah, he’s a very naughty boy

Even Corbynmania achieves nothing else, it really has been wonderful to see Tony Blair begin to come to terms with just exactly what people think of him. About damn time.