Dale Vince could lose £1.9 million in a 20-year-old divorce case because of this technicality

Dale Vince, the CEO of Britain's biggest green energy supplier Ecotricity, divorced his first wife in 1992 when they were both new age hippie travellers, penniless and largely living off state benefits.

But his ex-wife Kathleen Wyatt is now fighting to get millions of pounds in back-dated cash from him. One of Britain's top divorce lawyers told Business Insider that it's all down to a small paperwork technicality - they forgot to "seal off" the financial arrangements section of their divorce papers.

"If you don't close off the financial matters in a divorce case, you technically leave that door open for your former spouse to get in touch and ask for more money, if you do happen to make a lot more in the future," said Ayesha Vardag, the president of her own law firm, Vardags in London.

"If there is a huge financial disparity between the two parties, even later down the line, the courts like to help with wealth distribution. Sometimes the courts want to do nice things like that but fundamentally, it was a technicality at the time that led to this case going to the appeals stage."

"In divorce cases I have seen, some people will maybe pay a lot more money out in a divorce settlement in order to close off the ability for a former spouse to seek further financial compensation in years to come. Above all, you need to put a tick through that box to close off future claims in the settlement."

Dale Vince and Kathleen Wyatt's history

Vince now has a net worth of £107 million ($165 million) and his green energy supply business Ecotricity is worth £57 million ($88 million).

However, when he met Wyatt in 1981, he was just 19 and she was 21. Wyatt already had a child from a previous relationship. They were both broke. They had a son, Dane, in 1983. He now works for Vince's Ecotricity company.

They were still both penniless when they divorced in 1992. Vince ended up travelling to Spain with a new partner in a 30-year-old fire engine and continued to lead his hippie lifestyle years later. He did not make his fortune until the 2000s.

Currently, Wyatt lives in a council house with her unemployed son Robin, 21, jobless teen mother Jessie, 18, and her unemployed boyfriend Ashley Lloyd, 24, and their three-month-old daughter. Her eldest daughter Emily, 36, is currently in prison. They are children from two other partners.

Some 20 years after Vince and Wyatt divorced, Vince's former wife lodged a £1.9 million ($2.9 million) claim against him, despite their short-lived marriage predating the time he became a multi-millionaire from his business. While her initial claim was thrown out of the court in March 2015, Wyatt appealed the decision. This this time the Supreme Court ruled there was "no time limit" for claims for financial provision for ex-spouses.

To make matters worse for Vince, he is paying £500,000 ($770,573) in legal costs for both him and Wyatt. The law forces costs to be shared amongst the combined wealth of the parties. Since Wyatt is penniless, Vince has to pay the legal fees.