There used to be thousands of shire horses in Britain
Britain's heavy horse breeds are under threat with one - the Suffolk punch - reduced to a few hundred mares, say conservationists.
The Rare Breeds Survival Trust says the numbers of shire horses, Clysdale horses and Suffolk punch horses have dwindled to such an extent that their very future is at risk.
Although "heavy horses", as they are known, are renowned for their intelligence and gentle nature, encouraging more people to breed the horses in the UK has been become increasingly difficult.
For centuries, heavy breeds such as the shires worked as farm horses pulling carts and helping to plough the fields.
After the World War II, however, their numbers started declining. The need for increased food production meant more farmers used tractors for farm work rather than horses.
Most at risk
Dr Dawn Teverson, conservation officer at the Rare Breeds Survival Trust, says of the three breeds, the Suffolk punch is most at risk. There are fewer than 300 registered breeding females now left in the UK.
You are looking here at an icon for the UK and we don't want to let it go
Amanda Hillier, Suffolk Horse Society
"If it wasn't for a handful of breeders after the war, who kept this horse going, there would be no more Suffolk punch horses. It's absolutely crucial to our heritage and our future to save this horse.
"We have the responsibility to keep these breeds intact for future generations. If you do get to a very low number you could be talking about extinction," said Dr Teverson.
David Bakewell, from West Runton in Norfolk, has been breeding heavy horses for 25 years.
"The Suffolk punch is absolutely critical. As little as 100 years ago there were thousands of them," he said.
The Rare Breeds Survival Trust is working closely with breed societies such as the Suffolk Horse Society, which register the breeds, to encourage more heavy horses.
It is also monitoring the quality of the Suffolk punch breed to help maintain the breed's purity. State of the art computer software is being used to look at the genetic relationships and the different blood lines within the breed based on pedigrees.
Dr Teverson says the trust is spending a lot of money on a semen bank to help increase breeding, because it is easier to transport the semen around the UK than the horses themselves. The semen will be used in the future for conservation breeding.
Amanda Hillier, administrative secretary for the Suffolk Horse Society, says she is concerned about the current number of Suffolk punch horses but is quietly confident the numbers will improve.
She said: "You are looking here at an icon for the UK and we don't want to let it go. The breed has been at a very low ebb for decades because the need for these horses wasn't obvious. Now we are very keen to maintain skills for these horses so numbers will then increase."
The society is actively promoting breeding by giving grants to owners who breed horses and also running training courses to teach people the skills to get heavy horses working in agriculture again.
"There's been a definite marked increase in the breed recently. In 2007 there were 37 new foals added to the stud book, an increase on the previous year and there are 26 registered licensed stallions on our list, which is more than a few years ago. There is good news as well as bad," said Ms Hillier.
Shire horses are now found across the world in countries such as Germany, Italy, Australia and the US.
Andrew Mercer, secretary to the Shire Horse Society, says shires are increasingly popular abroad but it has been a challenge to encourage more breeders in the UK.
He says more shire horses are being used for showing, riding, and cross-country driving.
"We have been working hard to highlight the different leisure activities the horses can be used for, in order to encourage more breeders. These horses certainly have a future but only if there are successful breeders," he said.