Boxing promoters have offered Ed Sheeran a 1 million pound payday to fight his estranged cousin Jethro Sheeran, who performs as Alonestar, in a six-round celebrity grudge match in London next February.

The family feud began in 2014 over a remix and has flared again amid the fallout from Sheeran's Macklemore tour controversy. What started as a musical disagreement has curdled into one of the most bitter family disputes in British pop, played out in interviews, social media posts and diss tracks.

Jethro Sheeran has enlisted Joe Calzaghe, the retired undefeated boxing champion, as his trainer, a move clearly designed to signal he is taking the challenge seriously. The involvement of a genuine boxing great has added an unlikely sporting credibility to what might otherwise be dismissed as a publicity stunt, and suggests the bout is being planned with professional ambition.

Celebrity boxing has become a lucrative industry, with grudge matches drawing huge audiences online and at the gate. Promoters have been quick to spot the commercial potential in a genuine family feud involving one of the biggest-selling musicians on the planet, and the six-round format promises a spectacle rather than a serious contest.

Ed Sheeran has not publicly responded to the offer. The singer, known for his low-key lifestyle despite his enormous fame, would be an unconventional boxing debutant, though his competitive streak is well documented and he has never been one to back down from a challenge.

Whether the fight happens remains to be seen, but the offer alone has ensured the Sheeran family feud stays in the headlines. For Jethro, it is a chance at the spotlight that has eluded him throughout his music career; for the promoters, it is potentially the most talked-about celebrity bout of the year, and the countdown to February has already begun.

Family feuds in the music industry are nothing new, but few involve a star of Sheeran's magnitude. The singer has generally kept his private life out of the spotlight, making the public nature of the dispute all the more striking. Jethro, who has pursued his own music career with limited commercial success, has been vocal about feeling overshadowed, and the boxing challenge is the most dramatic escalation yet. Whether Sheeran takes the bait is another matter: with a global touring schedule and a family of his own, stepping into a boxing ring would be an extraordinary detour. Until Sheeran responds, the promoters' million-pound offer will keep the rumour mill turning.