Despite the rise of the electoral professional party, there are reasons why UK political party members are still important:-
Membership fees provide a source of income for the parties. Their importance varies from one party to the next. In 2014 membership income was 23% of Green Party income, 15% of Labour Party income, 9% of Liberal Democrat Party income but just 2% of Conservative Party income. In addition, members raise funds that can be used in local campaigning.
There is increasing evidence that local campaigning increases support for a political party. Even when the received wisdom was that the national campaign and a uniform swing decided general elections, the Liberal Democrats showed that they could win council seats and, building on that base, win Parliamentary seats through local activity.
From the 2001 election onwards, it was increasingly obvious that party success varied from seat to seat. This was partly through the work of sitting MPs in helping people locally and being involved in the community but academic studies have shown that levels of activity by local party members increased the party vote.
Over half of voters, in one survey, were impressed by someone from a political party appearing on their doorstep. As the public became more disillusioned with national politicians, it is more important for local parties to regain trust by taking up local issues and running campaigns on topics that matter to local people. Local parties have been encouraged by the centre to get involved with community organisations.
Party members select local and Parliamentary candidates and so have an influence on the make-up of the Parliamentary party.
From the mid-1990s Conservative Associations increasingly picked candidates who were Eurosceptic causing headaches for the leadership.
The national parties have intervened, though, to ensure that local parties do not pick only white male candidates. Labour required many constituencies to chose from an all-women shortlist and David Cameron drew up a central list, which became known as the A list, with more ethnic minority people and women which local parties had to pick from.
In all the political parties, it is now the members who elect the party leader. Labour extended this by allowing supporters and members of affiliated unions to register and also take part in the vote.
The nomination of candidates still remains with MPs, however, and the triggering of a contest against the current Leader in the Conservative and Labour parties can only be initiated by MPs. On occasion, such as the selection of Theresa May as leader of the Conservative Party, time pressures have taken this decision away from members. If you get your candidates down to two and one drops out there is no choice for members to make.
The Liberal Democrats, as well as MPs being able to trigger a leadership election, allow for 75 constituency parties to pass a motion of no confidence in the Leader.
It is difficult to imagine a political party that is not a vehicle for discussion of what policies are right for the country.
Members are unlikely to be satisfied with just canvassing at election time for whatever the leadership has decided.
The parties have mechanisms for members to get involved in policy-making. The Liberal Democrats have the most democratic organisation with party conference making policy and a Policy Committee, elected by members, which feeds proposals into the general election manifesto, although the leadership have ultimate control of what is in the manifesto. Labour used to be similar with Conference deciding policies and members electing the National Executive Committee which had a say in the manifesto.
In 1997, Tony Blair introduced a more complicated Partnership in Power process with control moving away from Conference to a National Policy Forum and policy commissions with the leadership having more control of the membership of these. Constituency parties can only send a resolution to Conference on an issue that has arisen since the last National Policy Forum report.
The Conservatives have tended to have a top-down organisation and, although William Hague introduced policy forums and votes by the membership on overall policy packages, the membership has little ability to change policy. Most members were unhappy with Prime Minister David Cameron’s policy on gay marriage but there was no means of passing a resolution opposing it. Perhaps this lack of influence has led to a decrease in party membership?