The story of lost teddy bears is a staple of children’s fiction, but for one Hampstead toddler the nightmare has turned to reality.

Three-year-old Sienna Appadoo and Brown Bear have been inseparable since she was tiny when her grandfather gave her the cuddly toy.

The teddy bear was a regular fixture at Sienna’s nursery in New End before the fateful day when Brown Bear was accidentally dropped during a busy shopping trip – never to be seen again last Tuesday (June 12).

When Sienna’s mother Abijah Conquest and father Marc Appadoo realised the loss, they helped Sienna launch a village-wide bear-hunt for the missing toy, fly-posting lampposts with notices offering a �50 reward for the return of Brown Bear.

On the poster appeal Sienna says: “He is my very first bear I’ve had him in my whole life. He has a bitten nose and a worn-out yellow tag with red writing on his ear. If you find Brown Bear can you please call my Mummy or Daddy.”

Her father, 30, from Heath Street in Hampstead, said: “She has woken up a few times in the night saying ‘Where is Brown Bear? I miss him’.”

Like fictitious bears before him such as Super Ted and Paddington Bear, Sienna has invented her own story to explain Brown Bear’s disappearance.

Mr Appadoo said: “She has developed her own story that he has gone on an adventure.

“Brown Bear was the one toy she developed an attachment to from all the toys she was given.

“She’s actually taking it very well. We thought she was going to be traumatised, but I think we have actually been the bigger wusses.”

Ms Conquest, 26, added: “I feel like the worst mum in the world and I think she has come up with the idea that Brown Bear has gone on an adventure for our sakes as much as hers.”

The Steiff bear was lost somewhere near Hampstead Tube station at around 4.30pm as Sienna and her mum made their way home.

Mr Appadoo, who is studying to be an accountant, believes another tiny tot might have picked Brown Bear up from the station floor.

“One of the station staff remembers seeing a bear on the floor and a little girl picking it up,” he said.

Sienna will celebrate her fourth birthday next week without Brown Bear.

But she has been given a replacement toy – Rosie Bear - while the search continues.

If you have seen Brown Bear please call 07860 525 763 or 07782 298 868