The widower of a woman killed by a train after serious safety blunders at a level-crossing near Marlborough has launched a claim for more than £500,000 damages from Network Rail.

Succesful cookery writer Julia Canning, 55, was hit by a train at the Fairfield crossing while walking her dogs near her home in Church Street, Little Bedwyn, in 2009.

Network Rail was fined £356,250 at Southampton Crown Court in June 2012 after a judge found that it had breached health and safety laws.

Mrs Canning's husband, the honourable Spencer Canning, 61 - the eldest son of the 5th Baron Garvagh - launched legal action against Network Rail for damages arising from the mother-of-three's tragic death. Network Rail has admitted liability for the fatal accident but is set to fight the chartered surveyor in a trial next month over the value of his claim.

Today, a High Court judge heard an application by Mr Canning, of Bottlesford, near Pewsey, to admit new evidence in relation to his wife's income at the time of her death.

Mrs Canning was struck by the First Great Western 17:11 service travelling from Newbury to Bedwyn on May 6, 2009 while walking her dogs, Tigger and Jazz.

Following Network Rail's fine, the Office of Rail Regulation said: "The criminal charges resulted from Network Rail's failure to act on substantial evidence that pedestrians using the crossing had insufficient insight of approaching trains.

"Pedestrians were therefore exposed to an increased safety risk when using the crossing."

Today, Robert Glancy QC, for Mr Canning, said "liability is now admitted in full" by Network Rail.

However, lawyers remain in dispute on the issue of Mrs Canning's earning power, which will have a crucial impact on the amount of her widower's damages payout.

Mr Glancy said Mrs Canning worked as a freelance publisher and editor of cookery magazines and books but also as a director of her husband's property investment business, Asset Plus One Ltd.

The QC added that Mrs Canning, who owned shares in the business, received dividends and pay from the company for the "substantial" role she played in running it.

Mr Glancy said Mrs Canning was "responsible for the company website" and "accompanied clients to business events", as well as "acting as a sounding board for her husband's business ventures".

However, Network Rail disputes the importance of Mrs Canning's role in the company.

Forensic accountants for both parties have analysed the couple's finances and remain split on the issue, Mr Glancy explained. The QC today asked the High Court to admit new evidence in the form of a witness statement made by Mr Canning, which sets out the nature of his wife's earnings from Asset Plus One.

He said it would add "explanation and clarification" of disputed facts bound to arise in the trial and that Network Rail's objections to its admission were "all froth and lacking in substance".

But Jonathan Watt-Pringle QC, for Network Rail, said the application had been made late and that Mr Canning's statement contained "new assertions" from those initially put forward.

The QC insisted that, before Mrs Canning's death, her income was "modest" while her husband's was "very substantial". He claimed that there had previously been "no suggestion at all that Mrs Canning made any practical contribution" to her husband's business.

Mr Watt-Pringle said that Mr Canning's original case was that his wife planned to rapidly increase her income by "riding the wave of popularity" of cookery literature, to bolster his finances after he suffered a health scare in 2009.

As such, the QC argued, the bid to admit new evidence was an impermissable attempt to widen his claim just a month before the trial is due to be begin.

Judge David Mitchell reserved his judgment on the issue. The full hearing of Mr Canning's case is due to begin at the High Court in May.