Chris Tarrant's ex-wife Ingrid Tarrant has opened up about the way she discovered he was having an affair. Ingrid, 70, suspected the presenter, 78, was up to no good 15 years into their marriage, which began in 1991.

At the time, the presenter denied that he was having an affair when she confronted him about her suspicions, but she didn't believe him. She recalled: "Something was telling me he was lying. So, I thought the only way to be sure is to put a private detective on him."

Ingrid said, after realising that getting into his car to put a tracking device inside it was tricky, she came up with a lie on why she needed to borrow his vehicle. After he agreed to lend her his car, she recalled: "It took them ages to fit it [the device]."

Ingrid also hid a phone in the ex Who Wants To Be A Millionaire? host's second car, which would show his location.

She added on the Suddenly Single podcast: "I had to keep secretly charging it and there were moments when I thought, 'This is insane'.

"I'd be quietly getting the keys, shimmying out to the car to get the phone and charge it."

Ingrid recalls having "many sleepless nights" during the process, particularly as he woke up early in the morning.

However, her persistence paid off as she realised her gut instinct was right the whole time.

Ingrid was presented with a picture which proved Chris' affair, and while she knew it was happening deep down, she admits it still came as a surprise.

"Call me naive, but I was so surprised. I had to have a photograph so there was no mistake," she added.

It turned out that the presenter had been seeing a 50-year-old primary school deputy headmistress for seven years.

After his affair hit the headlines in 2006, he released a statement apologising for the hurt he had caused.

Chris said he was "deeply sorry" and added: "I have only myself to blame for the breakdown of my marriage."

The former couple, who have two children together, finalised their divorce after 16 years of marriage in 2007.

These days, Ingrid says she is happily single and celibate. She said: "Do I really want to get back into all that with another man?

"I don't know that I do! I have a great social life, I like having an empty nest and I don't feel lonely at all."

Chris remains with his long-term partner Jane Bird, whom he met shortly after his and Ingrid's divorce was finalised.