An NHS worker whose employers tried to make her redundant while she was abroad on holiday has won her case at the Supreme Court.

Before her trip to Egypt in April 2011, Sandi Haywood asked Newcastle upon Tyne Hospitals NHS Foundation Trust that no decision be taken on her possible redundancy during her two-week absence.

Notice given on or after April 27 would expire on or after Mrs Haywood's 50th birthday on July 20, which meant she would receive a higher pension.

When Mrs Haywood, of Gateshead, Tyne and Wear, got back on April 27, she found a letter - sent by recorded delivery on April 21 and collected from the sorting office by her father-in-law - which gave notice of termination of her employment.

The High Court and the Court of Appeal backed her claim that her 12 weeks notice did not begin until April 27 when she received and read the letter.

The trust had argued that her contract should have terminated 12 weeks after the letter was sent, resulting in a significantly reduced pension.

Mrs Haywood was awarded just under £400,000 in past and future losses although no payment has been received pending the Supreme Court hearing.

On Wednesday, by a majority of three to two, a panel of justices dismissed the trust's appeal.

They ruled that notice of termination of an employment contract, when given in writing and posted to the employee's home address, starts to run when received by the employee and they have either read it or had a reasonable opportunity to do so.

Lady Hale said: "Given the vast numbers of working people who might be affected by this issue, it is perhaps surprising that it has not previously come before the higher courts."

Mrs Haywood, who worked for the NHS for more than 30 years as an associate director of business development for Newcastle and North Tyneside Primary Care Trusts, said: "I'm of course delighted by the outcome of this case and relieved the matter has been resolved.

"As I've said since the beginning, I have just wanted to be treated fairly and wish that the trust recognised this rather than pursuing the matter and spending significant legal costs which could have been money spent on patient care."

Jane Anderson, of law firm Irwin Mitchell, which represented Mrs Haywood, said: "This is a significant case particularly as it provides a definitive answer to the question of when does the notice period start if an employee is dismissed on written notice posted to them as opposed to communicated to them in person."

Mrs Haywood's counsel, Caspar Glyn QC, said the case was legally significant in that it created a new implied term in every employment contract.