Shan Lambert, who was married for 23 years to the founder of the Adscene newspaper chain, was awarded �7.5m last year and is now back in court asking for another �2.6m.

She is claiming at the Court of Appeal that she was equally responsible for building up the business and is entitled to half its �20m selling price.

Last year, the High Court awarded Mrs Lambert Ringleton Manor, the home she shared with her husband Harry and their two children near Sandwich in Kent.

The worth and endeavour of the wife is equal to the worth of the husband and it is therefore fair that the fruits of the partnership should be divided equally

Nicholas Mostyn QC

It is worth �1.4m and she was also given the accompanying Ringleton Lodge, which is valued at �250,000.

She was also allowed to keep assets worth �2.8m and was given a lump sum of �3,152,732.

Nicholas Mostyn QC, representing the wife, told three appeal judges that his client's case was "of great importance to married women".

He said women who contributed to a marriage were entitled to equal shares of the spoils of the relationship.

Equal partnership

If her High Court case had been heard anywhere else in Europe she would have been awarded 50% of the assets she had built up with her husband, he said.

"The worth and endeavour of the wife is equal to the worth of the husband and it is therefore fair that the fruits of the partnership should be divided equally."

The laws of this country should reflect the fact that marriage is a true and equal personal partnership, said Mr Mostyn.

He added the �7.5m award last year was just 37.13% of their total assets.

Pot of gold

Mrs Lambert was a director of Adscene since 1978, and of the main group since 1981 through to its flotation in 1987 until it was sold in 1999.

Mr Mostyn said his client had also raised the children of the marriage and ran the family estate but her husband had "witheringly described his wife's contribution to the marriage as revolving around children and microwave".

He said he was asking the court to decide "what is marriage?".

He also argued that, Mr Lambert, who went to live in Monaco after selling his business, had in 2000 and 2001 made a series of imprudent and "highly speculative" investments, which had the effect of reducing the "pot of gold" by more than �1.3m.

Mrs Lambert should not have had to pay the price for that and her husband's losses should have been taken into account when assessing her payout, he told the court.

The case continues.