A leading player in Edinburgh's financial community yesterday emerged as one of the alleged aggressors in what could result in Britain's highest ever sex discrimination compensation award being paid out.

Marrack Tonkin, 36, a Scot who is company secretary and head of city finance company F&C Asset Management's office in the capital, is alleged to have subjected Gill Switalski, 51, who was head of the firm's legal affairs, to an 18-month campaign of harassment.

The 51-year-old twice married mother claims she was left "disabled" after being driven out of her job following a sustained offensive, which included alleged bullying, intimidation, sexual discrimination and victimisation.

Mr Tonkin, a father-of-three who lives in Balerno, Midlothian, was born in Scotland and played at youth and under-21 level for the national rugby team. He also played for Currie rugby club, last season's national Premiership champions, from 1990 until about 2001.

He was appointed to the role of company secretary and head of the Edinburgh office at F&C Asset Management Ltd - the modern day incarnation of both ISIS and Ivory & Sime - where there are about 100 staff, in 2002.

He previously held a number of posts within F&C's headquarters in London after joining the firm in 1989.

An employment tribunal ruled in March that Mr Tonkin and Peter Cole, F&C Asset Management's head of human resources, had sexually discriminated against and harassed Mrs Switalski, who was once named one of the legal world's "Hot 100".

The judgment said: "The purpose or effect of Mr Tonkin and Mr Cole's actions was of violating her dignity by creating an intimidating, hostile, degrading, humiliating or offensive environment'."

The tribunal said she should be awarded compensation over her claims against her former employer, which controls assets worth more than £102bn.

Her lawyers estimated the cost of her psychiatric damage, loss of earnings, pension and career prospects at £13.4m.

However, F&C Asset's lawyers claim the total cost of the ruling could be nearer £19m. The largest previous compensation payment in a similar case in the UK was £6.5m paid to bond trader Allison Schieffelin in 2005.

F&C Asset management vehemently denied Mrs Switalski's claims and lodged an appeal against the ruling.

The tribunal heard that Mrs Switalski held down her £140,000-a-year City job while running her own legal training website and developing a series of multi-million-pound properties.

She also cared for her two disabled sons, one of whom has cerebral palsy and the other who has Asperger's syndrome, a form of autism.

The self-confessed workaholic once described as a "whirling dervish" now sleeps for several hours during the day and is on prescription drugs. She cannot manage her website, properties or even read a newspaper.

Mrs Switalski sold her family's £3.4m home in Surrey to help pay for her legal battle against F&C Asset Management. The employment tribunal heard her world slowly fell apart at the hands of Mr Tonkin, who was her new line manager.

She put in flexible hours and wanted to work from home to regularly to devote time to her family.

But Mr Tonkin allegedly began questioning her time away from the office, her holidays and her expenses after he was put in charge of her team and its budget in 2004.

The tribunal heard that he became "fixated" with her working hours, even though it was claimed she continued to meet all her targets, and quizzed her juniors about whether she was in the office.

Yesterday, at an appeal tribunal, lawyers for the firm asked for a re-run of the original hearing, claiming that the employment hearing did not consider its employees' side of the story.

Monica Carss-Frisk, QC, representing the company, said: "My clients do not know why we lost. A wealth of evidence was simply ignored by the tribunal.

"If you have a claim for £19m it cannot be said it is disproportionate to go to a different tribunal to deal with it afresh."

She urged the appeal panel, headed by Judge Peter Clark, to reject the findings made by Central London Employment Tribunal and to refer a re-run to a different place.

Mrs Switalski had claimed that Mr Tonkin had "micro-managed" her work and quizzed members of her team about her working habits and time spent out of the office.

But Ms Carss-Frisk said Mr Tonkin had a legitimate reason for doing so, telling the appeal hearing: "There is considerable evidence the claimant spent a large proportion of her time on matters not related to F&C but her own businesses."

The hearing continues.