Shell Bay beach in Fife.

Karla Barr, 34, was on a beach in Fife when she discovered a white bottle with stars on it.

After she allowed her children, Jessica, 12, and Fraser, 10, to open the bottle they were horrified to discover there was not a treasure map or ancient letter as they expected, but instead an advert for an escort agency with an x-rated image.

Speaking to the newspaper The Daily Star, she explained: "When we were about to leave my daughter said 'look at that bottle someone has drew on it... maybe it’s a message in a bottle.

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"I said 'I doubt it but let’s look.'"

Karla took pictures of the children as they opened the bottle.

She said: "My son and daughter opened it together and said 'it is a message in a bottle'.

"It looked like someone had put a lot of effort into. The letter was rolled up in a plastic wallet and then stuck into a decorated bottle.

"We took a photo holding the contents and then started to open it excitedly..."

Karla said she was "surprised, confused, shocked and amused" at what they found inside.

It was an advert for an 'escort service' called, "The North Vikingsea freelance escort babe agency" with an explicit picture of a woman.

Karla said: "It looked like a newspaper, on it someone had stencilled the writing with pen describing 'The North Vikingsea freelance escort babe agency' and their 'beautiful babe Sophie'.

“We then decided it was best to roll it back up and leave it for someone else to find."

She added: "The questions then came about who would have done that, what was it about and why there was hair on it... we swiftly changed the subject.