Alan Williams is locked in a bitter High Court battle with guitarists Mick Clarke and Steve Etherington and singing drummer John Richardson over who has the right to use the band’s name.
He says they went behind his back in 2018 to form a breakaway band and claims his company, Alan Williams Entertainment, has the right to stop them using the name.
But they say they only decided to carry on playing without him after he announced he was going to live in Australia.
Judge Pat Treacy has now reserved her decision in the case.
The Rubettes stayed together for decades after 1974 hit Sugar Baby Love – a blend of glam-rock, doo-wop and high-pitched vocals – sold 10million copies worldwide.
In 2002 keyboard player Bill Hurd split to form his own breakaway band.