The chief executive of NHS 24 was given more than £50,000 of taxpayers' money when he quit suddenly after serving the helpline for less than six months.

Sandy Forrest, who resigned from the health helpline amid mysterious circumstances, received half of his £95,000 annual salary, and an ex-gratia payment of £5000, as part of his severance package, even though he spent just 24 weeks in the post.

Opposition politicians are now demanding an explanation from Health Secretary Nicola Sturgeon, after the payments were revealed in answers obtained by The Herald under the Freedom of Information Act.

Mr Forrest, 54, is a former deputy chief constable and is reported to receive a sizeable police pension already, understood to be worth around £45,000 a year. He took over NHS 24 at a time when it was widely perceived to be recovering from crisis. In the early years, the helpline had been unable to cope with the volume of calls from patients when GP surgeries were shut, but it turned a corner under the leadership of former chief executive John McGuigan.

On May 1 this year, Mr Forrest succeeded Mr McGuigan and claimed to be enjoying the job. But he left suddenly halfway through October, bringing fresh upheaval just weeks after a sheriff said a toddler's death in April last year - before Mr Forrest's tenure - could have been avoided if NHS 24 staff had called an ambulance.

The service maintains Mr Forrest chose to leave immediately because he held a number of external commitments which he could not balance with his chief executive duties. Despite this, officials say the "terms of his resignation" included a payment of £47,516, less tax and national insurance, in lieu of his six-month notice period.

Ross Finnie, Liberal Democrat health spokesman, said last night: "We previously understood that Sandy Forrest had simply resigned his post as chief executive of NHS 24. We now find that NHS 24 has paid him substantial compensation on leaving. This raises serious questions about the circumstances surrounding his departure from NHS 24. I will be calling on the Health Secretary to clarify the matter, as it involves the payment of public funds."

Mr Finnie is writing to Ms Sturgeon seeking an explanation.

Mary Scanlon, Tory health spokeswoman, also questioned the payments. She said: "Three nurses could be out there serving, supporting, and treating patients rather than £52,000 being spent for someone to sit at home. That is a waste of public money."

Ms Scanlon added that there still appeared to be problems at the heart of the helpline. She said: "NHS 24 has been beset with problems from the start and when a chief executive quits after less than six months in the job, this can hardly inspire trust and confidence in the future of the organisation."

Mr Forrest, who could not be contacted yesterday, was highly regarded as a policeman. He rose to the rank of deputy chief constable with the police inspectorate. When he left this post in 2003, it is reported that he received half his £90,000 salary in pension and a six-figure lump sum. He then went on to direct the Council for the Regulation of Healthcare Excellence, which oversees the regulation of healthcare professionals. He applied for the post of chief executive of NHS 24 and was apparently chosen in February from a number of very high-calibre candidates. The Scottish Executive, as the Scottish Government was then known, approved the appointment.

The Herald asked why NHS 24 did not ask Mr Forrest to work his notice, but still paid him for the period.

In a statement, the helpline stressed the chief executive role demanded an immense amount of energy and time and that it was Mr Forrest's decision to step down with immediate effect because it was impossible to balance the job with his external commitments. A spokeswoman added: "Service is much more than any one post. What is important is patient care, where our service has continued entirely as normal under an executive team and by staff with an enviable level of skills and an outstanding knowledge of the service.

"The board and executive team have already laid out the five-year strategy and we reassure the public that NHS 24 remains committed to delivering the best possible service as part of the wider out of hours health care in Scotland."