A wealthy businessman who says he and his former ''wife'' were never legally married may still have to pay out even if a judge rules in his favour, according to a specialist lawyer.
Asif Aziz, who is in his 40s, says he and Tagilde Aziz, who were both born abroad, obtained a ''fake'' marriage certificate so a child they had adopted could get a passport.
He wants a British High Court judge to rescind a divorce pronouncement.
Mrs Aziz, who is in her 50s, disputes his claim and says they were married.
She says they were together for 20 years and she is entitled to a ''fair share'' of a £1.1 bn marital pot.
Mr Justice Moor is expected to decide whether the marriage was valid after analysing evidence at a trial in the Family Division of the High Court in London later this year.
The judge has been given detail of the dispute at a preliminary hearing.
Mrs Aziz says a Muslim ceremony of marriage took place in Malawi in 2002.
Mr Aziz, founder of London-based property business Criterion Capital, says no ceremony took place but a marriage ''certificate of convenience'' was issued.
Specialist divorce lawyer Hetty Gleave, who is based at Hunters Solicitors, says Mrs Aziz may get a payout in any event.
"Even if Mr Aziz is successful in proving that his marriage was not recognised in Malawi, and so is invalid in this country, he should not assume that Mrs Aziz is not entitled to any financial relief," she said.
"As long as she has sufficient evidence after 15 years to show that they both intended to be married and lived their life as man and wife, then her financial claims against him remain open."
She added: "It would be a cold-hearted judge who did not look with tender sympathy on such an applicant after such a long relationship."