The reason that Jeremy Corbyn has won the contest to be Labour’s new leader today is obvious.

Many people are seeing the starkest cuts of their lifetimes to the public services that their families rely upon and the tax credits that enable them to just about keep their heads above the water.

The world of work never felt more insecure, characterised by the proliferation of zero hours contracts, endemic low pay and huge worries about where the axe will fall next for those who work in the public services.

Amidst this sense of hopelessness Jeremy Corbyn has represented a clear alternative, arguing convincingly that we do not need to accept the cosy consensus on everything from austerity, PFI and public sector pay – right through to welfare reform, nationalisation and Trident.

Now comes the difficult bit. These may be historic times. But they are also hard times. The new leader of the Labour Party will take up his new position facing not just the high expectations of the hundreds of thousands who voted for him, but also the need to speak up for those who are being trampled by this callous government. As such he faces a formidable to-do-list.

Top of the list is turning the party into an effective opposition. The Tory government have had an easy ride since May. Whilst Labour has faced inward the Tories have made all of the running – introducing a ‘national living wage’ and claiming that they are now the party of the working people.

They have done this whilst at the same time making massive cuts that will impact on the living standards of millions. On Monday they will move to a second reading of a bill that seeks to undermine the right of ordinary working people to withdraw their labour and silence their political voice. This must be opposed and the rank hypocrisy of the Tories exposed.

Next on the list, Jeremy has the lead role in unifying the party. This is not his responsibility alone. All party members must share responsibility for moving on from what has at times has seemed an overly long and bad tempered leadership contest, but Jeremy needs to lead from the front.

And then, we need to build an effective campaign force in the country that will see Labour over the line at the 2020 General Election. There will be many milestones on the way, including elections to the Scottish Parliament, Wales National Assembly, London Mayorality, as well as many local elections. To succeed in this endeavour Labour clearly has to learn the lessons from the 2015 election – reconnect with the voters we lost, but also appeal to the disaffected, who have stopped voting or have never voted.

Jeremy’s commitment to building a social movement for change has the potential to reshape politics in the UK. The challenges faced by working people, the young and the vulnerable demand nothing less.

Dave Prentis is the general secretary of UNISON