An elderly woman was recovering in hospital on Sunday after getting stuck up to her knees in mud on a riverbank for about 21hours.

Retired paediatrician Dr Sheila Hill, 82, spent the night battling to free herself from the boggy banks of the River Severn.

But her cries for help went unheard until a fellow dog walker discovered the exhausted pensioner and rushed to a nearby house to call emergency services.

Firefighters used a special rescue sledge to reach an exhausted Dr Hill who was then rushed to hospital by ambulance.

Police say she is lucky to be alive and would not have survived the night if recent freezing temperatures had not warmed up.

A spokesman for Gloucestershire police said: ''It is thankful that it happened on this night in particular.

''If it had happened on either of the last two weekends, when temperatures were at freezing or below, it would have been a different story."

Dr Hill was walking her two Jack Russell terriers near the Saxon church of Odda's Chapel in Deerhurst on Saturday afternoon when she slipped.

The popular public footpath running along the river is just over a foot wide and perilously close to the boggy riverbank.

She desperately cried for help but her pleas went unheard until a passing walker came to her rescue at 9am yesterday morning – some 21 hours after she got stuck.

The walker tried to pull her free but when this failed he ran 100 yards to the door of retired professor Peter Lord, 80, who dialled 999.

Mr Lord said: ''The man who knocked on my door was panicking and covered in mud because he'd tried to rescue her but couldn't get her out.

''He said she was in a pretty bad way and shivering but was still lucid.

''It's quite a quagmire down there, thick with clay and sticky mud which you sink into straight away – goodness knows what she was doing trying to walk down there.

"She's very lucky it was so mild last night or it would have easily killed her because she is very frail and elderly and could easily have got hypothermia."

A first responder paramedic unit arrived within 10 minutes followed by an ambulance. A police car and two fire engines also attended the scene.

A team of six firefighters used a rescue sledge to reach Dr Hill who was about a mile from her bungalow home.

Graham Parker, station manager at Gloucestershire Fire and Rescue Service HQ in Gloucester, said the woman was suffering from the effects of the cold.

"She was stuck just over her knees – somewhere between knee and thigh height – in the mud," he said. "Six firefighters were involved in dragging her back to the bank. She was very cold but otherwise did not appear to have any serious physical injuries."

Mr Parker said the mud created a vacuum which made it difficult to pull her clear.

The county air ambulance was scrambled from Strensham 10 miles away, but the woman was deemed well enough to travel to Gloucestershire Royal Hospital in Gloucester by road ambulance.

Locals say Dr Hill, who lived with her sister until she went into a nursing home is a fit and active pensioner who catches a bus into Tewkesbury most days. One villager said: "You would always see her with dogs. She would take one out in the morning and two out later in the day."

Villager Sheila Ryan was one of a handful of people who attended church in St Mary's, which is near the chapel, at 8am.

"It's really upsetting to think she was down there and we did not know," she said.

"She's a nice lady who gets involved in things like the WI and people will be very upset to think of this happening to her.

"A lot of dog walkers use the path, but it's quite remote and many of the houses are still empty after the floods."

An elderly neighbour said: ''I have known her for nine years since I moved in and she just loves her animals.

"She takes her dogs for a walk every afternoon and walks a couple of miles down the river. I'm very surprised that she got stuck like this because she knows the area so well."

Mr Lord's wife Brenda, 76, said locals wanted safety improvements and added: ''When you're down by the river there is only an area of about a foot to walk on.

''We've been trying to get the area made safer for a long time because it is so dangerous with the mud."