Cornwall is facing a political crisis because of reforms to local democracy, the failure of Westminster to understand the needs of the far south-west of Britain and Brexit, one of the UK’s longest-serving party leaders is warning.

Dick Cole, who is celebrating 20 years as the leader of the Cornish party Mebyon Kernow (MK), said he feared Cornwall would lose out financially under Brexit and argued that central government was not responding to the social problems the county suffers.

He also called plans to reduce the number of councillors on Cornwall council – from more than 300 when he became MK leader to less than 100 by 2021 – disgraceful. At present there are 123.

“Democracy is in crisis in Cornwall,” he said. “I think it’s a dangerous moment for local democracy here.”

Cole, known in county hall as the man in the woolly jumper, has become one of the most well-known and respected Cornish politicians. His party may have only four members on Cornwall council (and another 20-odd on town and parish councils) but they choose their battles well and their voices are heard clearly.

When Cornwall council sent a delegation to Westminster to argue that the Cornish should have their own nationality tick box at the next census, Cole was chosen to lead the delegation.

National broadcasters have also been giving MK airtime this year, though when deputy leader Loveday Jenkin appeared on BBC Radio 4’s Any Questions Jonathan Dimbleby blundered in describing her as being a member of the party for Wales.

As well as being a long-serving leader (Arthur Scargill pips him as leader of the Socialist Labour party with 21 years at the helm), Cole enjoys an astonishing level of loyalty from his voters. At the last election he won 83% of the vote in the ward of St Enoder, near Newquay.

Cole became leader of the progressive left-of-centre party in 1997 when devolution referendums took place in Wales and Scotland. MK hoped that this move towards devolution would also lead to the creation of a Cornish assembly.

Some 50,000 people – a tenth of the Cornish population – signed a declaration in 2001 calling for a Cornish assembly. It was delivered to Downing Street, but nothing happened.

“They ignored us,” said Cole. “That has been the real sadness of the last 20 years. We’ve got a strong case for devolution but it has not been heard. Central government just doesn’t get Cornwall in the way it gets Wales and Scotland. Cornwall doesn’t fit their jigsaw puzzle. Partly it’s a matter of geography – it’s a long way from London and Conservative MPs seem to see Cornwall as a good place to go on holiday but don’t understand the detail of the place.”

There have been highs. In 2014 the UK government announced that the Cornish people would be classified under the European framework convention for the protection of national minorities in the same way as the UK’s other Celtic people, the Scots, the Welsh and the Irish. The news was widely celebrated across Cornwall.

However, since then little has changed and the UK government was criticised by the Council of Europe for cutting funding for the Cornish language and not doing enough to raise the profile of Cornish life.

“The reality is that having recognised us, they have not followed through in the articles in the agreement. Within a couple of years they had stopped funding from the centre for the Cornish language,” Cole said.

He is also angry that the political integrity of Cornwall has been threatened by the possibility of a so-called “Devonwall” parliamentary constituency straddling Cornwall and Devon.

A second local government boundary commission decision – that the number of elected members on Cornwall council should be cut from 123 to 87 – also attracts his ire.

When he became MK leader there were more than 300 councillor posts on the county council and six district councils. The districts were disbanded in 2009 and replaced by one unitary authority. “We’re campaigning for democratic renewal but what we’re seeing is the opposite – the dismantling of our democracy and the growth of the influence of unelected bodies,” he said.

Though Cornwall was one of the areas that benefitted most from EU funding, its people voted substantially to leave the EU. Cole, a backer of the remain campaign, has concerns. “There’s a lot of nervousness about post Brexit. The UK government is liaising with the devolved nations but I don’t feel Cornwall is on the radar.”

Cole, who gave up his job as an archaeologist to become a full-time councillor, insists Cornwall is a great place to be. “There’s a growing confidence about identity,” he said.

As for MK, he believes the party can continue to wield more influence than its size would suggest. At the next general election the party plans to focus on one or two seats and see if it can make an impact.

“Our influence over the years has been much greater than size of the party,” said Cole. “Ours is a very loud voice.” Though independence is not an MK aim, he admires the determination of the Catalans to break from Spain and the Scottish nationalists’ 2014 referendum campaign. “You can take inspiration from the energy of those campaigns. We’re trying to say to Cornwall there’s a better way.”