Even if, as seems very unlikely, the private funding of political parties were to be banned as MaizieD suggests, we would not have a level playing field as long as so-called "think tanks" were uncontrolled.
There are think thanks aligned to various political positions but it is the right wing think tanks working in Tufton Street which have huge power and influence, whilst not disclosing the source of their funding.
According to Wikipaedia -
"55 Tufton Street is a four-storey Georgian-era townhouse on Tufton Street, in Westminster, London, owned by businessman Richard Smith. Since the 2010s the building has hosted a network of libertarian lobby groups and think tanks related to pro-Brexit, climate science denial and other fossil-fuel lobby groups. Some of the organisations it houses have close connections with those at nextdoor 57 Tufton Street, including the Centre for Policy Studies and CapX.
A group of these lobbying organisations, dubbed "The Nine Entities", used the building for biweekly meetings to coordinate policy and public messages. The nine lobby groups—the TaxPayers' Alliance, the office of Peter Whittle (a former deputy leader of UKIP), Civitas, the Adam Smith Institute, Leave Means Leave, the Global Warming Policy Foundation (the UK's principal climate science denial group), BrexitCentral, the Centre for Policy Studies and the Institute for Economic Affairs—were accused by former Vote Leave employee Shahmir Sanni of using the meetings to "agree on a single set of right-wing talking points" and "securing more exposure to the public".
This network is tied to major US funders of climate science denial and organizations supporting right-wing political causes including the Koch brothers of Koch Industries and Robert Mercer. The network works closely with British politicians, and also has extensive ties to populist right-wing parties in Europe, such as the Sweden Democrats and the Brothers of Italy."
en.wikipedia.org/wiki/55_Tufton_Street
