The two-stone cat that could not fit through a flap

The cat was "in such a sorry state" when she arrived at a rescue centre, the RSPCA said

An overweight rescue cat whose rotund 26lb (12kg) prevented her from fitting through a cat flap was "the largest I have seen", said one RSPCA worker.

The two-year-old - named Big Bertha at first by the animal charity - was found unfit and abandoned in a sports bag.

RSPCA staff have since put her on a strict and successful diet, dropping the early "cat-shaming" for the new name of just Bertha.

Now weighing 19lb (8.9kg), she will "soon be ready to find a new home".

Bertha's weight, caused by a "lack of exercise and lots of food", the charity said, was not her only problem when she was found by a member of the public in Birmingham's Calthorpe Park in October. Her matted fur was pulling on her skin too.

But despite being in "such a sorry state", the RSPCA said she was "doing really well".

Cattery supervisor Emma Finnimore said: "This is the largest cat I have seen in my 22 years working for the RSPCA."

A vet clipped away the matting but the weight still proved a problem at first, making Bertha too large to live in one of the charity's cat pods, Ms Finnimore explained.

Worker Emma Cureton, who looked after the cat at home instead, said she was "moving around a lot more", and was called "just Bertha" now, as a diet and exercise regime had made a difference.

Ms Cureton said Bertha had not been "physically too fit to stay at the cattery and couldn't fit through the cat flap we have", but she was on special food "to reduce her weight nice and slowly".

Bertha could not fit through a cat flap

Ms Cureton added: "When I brought her back home in October, she just literally came out for toileting and food and [it was] straight back to bed.

"[Now] she's up and down the stairs quite a lot, so it's just a case of just moving her about as much as we can."

The RSPCA worker explained Bertha's weight still had to be reduced but once vets had signed her off as medically fit, she would be up for rehoming and "people can apply for her online".

Bertha's first weight target is 7.4kg (16lb) and she will be reassessed by vets thereafter.

Ms Cureton said the cat was otherwise relatively healthy.

"She's quite good considering what she's been through," she said. "So she's a good girl really. She'll make a lovely cat for somebody."

Follow BBC West Midlands on Facebook, Twitter and Instagram. Send your story ideas to: [e-mail]