The Political Parties, Elections and Referendums Act 2000 required that all parties disclose their in- and outgoings with the Electoral Commission and that they declare large declarations (defined today as over £7500). A maximum of £30k in campaigning costs per constituency party was also introduced.
The PPERA is enforced with fines. For example the Leave campaign was fined £70k in 2018 for a rule breach.
The Political Parties and Elections Act 2009 strengthened its predecessor's provisions including limiting major donations to those made by UK residents.
Labour were traditionally funded by the trade unions, 96% in 1983 but Blair moved towards private donors and Miliband got rid of the automatic affiliation so that this figure had halved by 2016. Their donations rose again under Corbyn.
In 201968% of Conservative donations came from individuals.
A large proportion of Labour's funding since 2010 has been Commons/Lords short money
Both parties have been accused of selling peerages. For example Paul Drayson received a peerage having donated £1 million to Labour as well as a £32 million NHS deal for his company in 2002.
In 1997 the Labour Party received a £1m donation from the chief of F1, Bernie Ecclestone after the sport had been exempted from a ban on tobacco advertising.
In 2020 an admin error revealed that a £100mPPE deal had been given to a Tory donor.
Major Tory donor Paul Sykes donated depending on their EU policy, switching to UKIP at times.
State funding would avoid any bias or expectations from donors, meaning policy is directed purely at constituents, but it could be argued it is a democratic right to financially support a party you believe in.
State funding that is proportional to the vote would stop parties from purely targeting their campaigning at marginals as they do now.
Previous funding reforms have had limited success making a move to state funding more attractive.
State funding could limit spending in general and reduce inequality between parties, however it still be unequal if it is proportional and would only serve to further benefit large partiees.
State funding would force voters to fund parties they do not agree with through taxpayer money
By the 2024 general election the Conservatives had taken in 4 times the total amount of donations to MPs and APPGs since the start of the term, twice that of Labour.
In the run up to the 2019 election, Lord David Sainsbury made the biggest donation in political history of £8 million to the Lib Dems, accounting for over half of their total funding
Between 2019 and 2024 the average MP received around £25k while Johnson declared £6.5m in donations
Unite currently make up around 19% of Labour's donations