‘People asked us, ‘Are you crackers?’” says Gemma Paintin. She can see why. Along with fellow Bristol artist James Stenhouse, Paintin spent half of 2018 travelling around Europe in an old motorhome, recording love songs. Their epic trek took in almost 20,000 miles, 33 countries, 46 languages and 731 songs – each sung in their battered mobile studio, mostly by random strangers.

These ranged from a seven-year-old Greek boy singing the Kiss song I Was Made for Lovin’ You (“even the guitar parts”) to MEP Peter Simon, who laid down a German folksong. There was a singing security guard in Madrid and some lads in Leeds who bawled through Robbie Williams’s Angels. This, says Paintin, was “exactly how you’d expect a lad version of Angels to sound”.

The 731 songs form part of Oh Europa, a project that will see them broadcast from 41 beacons around Europe (accessed via an app). It opens today at the Transform festival in Leeds, where visitors will be able to hear up to 20 hours of recordings, go inside the motorhome, and even add a song to the library.

The intention was to explore “what Europe is and how we’re all interconnected”, Paintin explains over coffee in Leeds. But after the EU referendum, the project took on another shape. “We thought, ‘We have to do it now.’ Whether we’re in or out of the EU, we’re all going to have to find a way to live together. But we didn’t want to go around asking, ‘What are your views on the European Union?’ We thought, ‘What if we connect in a different way?’”

‘People realised they could be part of something potent’ … Gemma Paintin finds a singer in Greece. Photograph: Pelagia Karanikola

It certainly seems to have worked: the pair are amazed by how many people were lured in by the signs placed outside their van reading: “Do you know a love song?” Paintin thinks the fact that they have been a couple since their late teens helped. “Somehow, it’s more poetic to be asked to sing a love song by two people who are in love themselves.”

They were equally surprised by how emotional the experience became. “People found it very moving,” she says. “We’d explain, ‘Your voice will be broadcast with all these other voices.’ So a voice from Norway goes to Athens. A song recorded in Finland goes to Spain. A recording by Syrian refugee in Germany goes to the Russian border. People seemed to realise that they can be part of something very potent.”

The pair, who are both 38 years old, met while studying drama at Yorkshire’s Bretton Hall, creating Action Hero, as they term their ongoing collaboration, in 2005. One piece, Extraordinary Rendition, put a single person inside a cabin the same dimensions as a Guántanamo Bay cell. Oh Europa is their most ambitious undertaking so far. “It felt exciting,” says Paintin. “Then we’d think, ‘How are we going to do this?’”

Funding came from Arts Council England, European culture foundations and Action Hero partners such as Bristol’s Pervasive Media Studio, where the project was developed. The initial and biggest outlay – £12,500 – was on the motorhome, a 2001 model bought on Gumtree.

Roll up, roll up … collecting love songs at Germany’s Hambach festival. Photograph: Sarah Hähnle

Everything was going swimmingly – until August. “We’d just gone over the Swiss Alps and ended up on a hairpin bend when the gearbox went,” says Paintin. “Only first and fifth would work.” They got it to a garage and learned that fixing it would be a major job. “But the mechanic showed us that by getting to certain revs you can change gear without a gearbox. We had to do that for three weeks – from the Netherlands to Romania and back.”

Has the project changed their worldviews? “It made me realise how diverse the continent is,” says Paintin. “Britain, Norway, Lithuania, Serbia, Macedonia … These countries feel so different historically and culturally, and yet there’s something between us, even if it’s an agreement to stay in the same thing together. People say, ‘Everything’s so homogenous nowadays, everywhere’s the same.’ That’s not the case at all.”

Paintin was surprised by which songs proved most popular – not the expected Beatles or Queen hits, but German folksongs and Hungarian love songs. Some people sang in forgotten languages – and in France, they hosted a group of teenagers from Ivory Coast who sang in their native tongue. “Kids of 15, 16, who’d arrived in the country unaccompanied. It becomes about the journey of these languages.”

Paintin and Stenhouse (whose dad Peter, a Northumberland folk singer, contributed traditional Geordie song Cushie Butterfield to the project) are thinking about taking Oh Europa into leave-voting heartlands, but don’t want to politicise it too much. Perhaps surprisingly, the subject of Brexit didn’t come up that much on their travels, beyond the occasional “robust conversation”, says Paintin. “I get the impression that most people don’t want us to leave,” she says. “When we were passing between Hungary and Croatia, the border guard asked me if I voted for it and I said I didn’t but that lots of people did. He kept saying, ‘Very bad situation,’ and then just waved us through.”

‘People come back, again and again’ … a five-day stop in Athens.

Paintin says she could do Oh Europa for ever. The motorhome has a new gearbox, and there are plans for more treks, hopefully encountering more memorable characters, like the man in Kirkgate Market, Leeds, who “only sings at karaoke”. At first, says Paintin, he was too nervous to perform. “But he came back half an hour later with the words to the Tony Bennett hit The Good Life on his notepad – and the most incredible voice came out.”

• Oh Europa is at the Transform festival, Leeds, until 4 May. Then touring. Oh Europa’s website, will be livestreaming all the songs from 10pm on 3 May to 6pm on 4 May.