An administrator who suffered a life-threatening blood clot from long hours sitting at her desk has received a "substantial" sum in compensation.

Angela Lamberton, 53, of Leicester's West End, will have to take medication for the rest of her life to avoid another potentially fatal clot from developing.

Angela, an administrative assistant for HM Revenue and Customs in Charles Street, Leicester, developed the clot behind her knee after her working routine was changed so she was effectively tied to her desk.

Targets were set and routines changed so staff no longer had to leave their desk to complete work.

Angela had suffered a previous blood clot and, although it was successfully treated and she no longer had to take medication, she was told by doctors to take breaks from her desk every 15 minutes.

The old work routine meant she was naturally taking those breaks to collect work from the printer.

When the new system was put in place she complained to her line manager but was told she must abide by the new rules.

Within weeks she started to suffer pains in her legs. Her GP diagnosed a blood clot and she had to receive emergency treatment to disperse it.

She must now take blood-thinning medication on a daily basis and wear specialist stockings.

She is too frightened to fly in case she develops another clot and when driving must stop every hour to stretch her legs.

She must attend the hospital every four weeks and still suffers from tired and painful legs.

She said: "My whole life has been changed. I'm terrified of flying and, if we drive anywhere, it takes a long time because we have to take so many breaks.

"My legs are sore and what used to be a 20-minute walk to work now takes me over an hour.

"I felt I had no choice but to accept the new working system because my complaints were dismissed.

"Now I will be on medication the rest of my life and the fear that I will develop another blood clot will always be with me."

Angela had to take four months off work. She contacted the Public and Commercial Services Union, which instructed Thompson's solicitors to pursue a claim for compensation.

HM Revenue and Customs admitted liability and settled out of court.

Pete Lockhart, national officer for HMRC at the PCS, said: "It is disgraceful that Angela's complaints were ignored despite her medical history. It is a classic case of management putting targets above their staff's health. It should never have taken the threat of legal action for Angela to be allowed to take a break from her desk."

Peter Magee, from Thompsons Solicitors, added: "Angela must live with the threat of another potentially fatal blood clot for the rest of her life. She argued that the new working system was damaging her health but was ignored. Employers must make sure they take into account their employee's physical ability to undertake a job and must be prepared to make allowances."

An HMRC spokesman said: "We cannot comment on individual cases. However, as an employer of 83,000 staff HMRC takes staff welfare very seriously, ensuring we implement all work place legislation and work closely with trade unions."