After watching a news report about how the Cambridgeshire Police force control room was looking for more staff, she wrote a letter to Chief Inspector Mike Winters to offer her help.

Mrs Pickering, of Brookfurlong, Ravensthorpe, Peterborough, became a telephonist after leaving school as a teenager, and worked on a military switchboard in Germany for about 10 years during the '80s.

In her letter, she said: "I know I am an elderly person to a lot of you people. I am 72 years of age now and retired.

"I was wondering if I could be of any help to you. I have not forgotten any of my switchboard skills and if need be, I could fit in with anything."

Touched by her enthusiasm, Ch Insp Winters, who could not offer her a volunteer position as she had asked, invited her on a special tour of the 999 centre, at the force's headquarters in Hinchingbrooke, Huntingdon.

Ch Insp Winters said: "It was a heartfelt plea. She was offering her services for free because she just wanted to help.

"Inviting her to the 999 centre was the least we could do"

The pensioner came with her granddaughter, Michelle, and her granddaughter's husband, police community support officer Matt Smart, and after being shown the computerised telephone system, how CCTV cameras could zoom in on her house, how 999 calls are received and dealt with and how the switchboard works, she said she was "gobsmacked" by the pace of technology.

She said: "I thought the control room was fantastic. I know it has been a few years, but it's completely different to what I was expecting. I was a qualified telephonist since I left school at 15.

"The first boards were cord boards. I've never had anything to do with computers – even the biggest military switchboards were just switches and lights.

"That was a big place, but this is something else. I'd never seen anything like this before.

"The inspector explained how everything worked, and I was very impressed.

"I would be tempted to work there."

Mrs Pickering also praised the police in her neighbourhood for making her feel secure and being approachable, especially after she suffered two break-ins.

"The police here in Ravensthorpe stop to have a chat. They make me feel safe," she said.

Twenty years ago the control centre was a small room in the roof area of Thorpe Wood police station, in Peterborough.

It had a telephone switchboard for taking calls and radio control that was used to pass information to officers.

Today, there is a dedicated control centre in Hinchingbrooke. Emergency calls come in through computers, with answering calls and relaying information all done through touch screens and a head-phone.

The centre takes an average of 450 calls a day.

Mobile phones mean the 999 centre can take dozens of calls in 10 minutes – many reporting the same incident.