Jilly Thomas-Scarrott put her cardigan into her handbag before going into the changing rooms at Marks & Spencer.

After trying on two pairs of trousers the 35-year-old gave one back to the assistant and paid for the other at the tills.

But seconds after walking back out into the Cascades Shopping Centre in Portsmouth she was stopped by at least 10 security guards.

She was then marched back into the store, taken into a room and accused of shoplifting.

The security guard accused her of stealing a cardigan – which was her own – and a pair of trousers, which she had the receipt for.

When Jilly proved she hadn't stolen anything she said staff at the store simply asked her to sign a form and let her go.

She said she was appalled at the way she was treated and has written to Marks & Spencer to complain about the incident.

'It's just horrendous,' she said.

'If there had been one or two people it wouldn't have been so bad. But there were about 10 people surrounding me.

'They didn't even tell me why I was being taken back into the store. It was quite frightening.

'I do like the store, I'm always buying things from there. I will go back there one day, but not in the near future.

'I could see all the people looking at me – they probably thought I was a thief. I am a very honest person and I have never been in trouble in my life. So being accosted by 10 people, then not being explained what was happening and being spoken to very aggressively was extremely scary and upsetting.'

Marks & Spencer apologised for the mix-up.

A spokesman said: 'We are extremely sorry for what happened to Mrs Thomas-Scarrott as our approach was clearly over zealous on this occasion.

'We have spoken to Mrs Thomas-Scarrott directly to apologise for the way the situation was handled and have invited her into the store to meet the store manager to discuss her experience.

'We hope that this will help to restore her faith in Marks & Spencer.'