Father-of-two Ben Treuhaft, 66, created the makeshift dwelling in Edinburgh after being kicked out by his wife from the family home in Morningside.
He has since moved in with new girlfriend, Mirka, who he met on the beach, and the couple stay at her Portobello flat.
However, New York-born Mr Treuhaft has so far refused to remove the tent and has now moved a giant pianola-style piano onto the site in protest at council efforts to evict him.
He says he will fight attempts to close down what he describes as a public art installation.
Mr Treuhaft said: "The council have given me a notice that they are about to start eviction procedures. They sent a fellow over with a notice [on Thursday night].
"They have given me until Wednesday to formally appeal the decision to try and evict me and if I don't then on Thursday there's a court date at 9.25am at the Sheriff Court.
If I don't appear they will kick me out within 48 hours, but if I do appear, they're going to lose the case. So I'm going to appear.
"They have been fair with me and I have been fair with them, but they have said some untrue things in their complaint so that will be good for me."
He added: "This is called the Portobello People's Public Piano Project. It is an excellent piano and anyone can play it any time they want.
"We never close. It's basically open 24/7 because it's a tent.
"It's a sort of work of art. It's a public piano, it's called pian-archy."
Mr Treuhaft travelled the world with his piano business, the Underwater Piano Shop, before settling in Edinburgh. He is the son of Jessica Mitford, who rebelled against her fascist upbringing, ran away to Spain and married a Communist nephew of Winston Churchill.
An Edinburgh City Council spokesman said: "We have received complaints from members of the public and we have growing concerns about the safety of the tent and its contents. Court papers have been served on Mr Treuhaft.
"If he does not remove the tent and contents voluntarily, we will remove them in the coming days."