By Sarah Mukherjee Environment correspondent, BBC News

Winnie, a huge feed eater, narrowly escaped being "sausaged"

A creamy sliver of crescent moon still hangs in the pink, gold and lilac dawn, perfectly reflected in a mirror-still River Thames.

There's no doubt the journey to Vitality Farm, home of Winnie the pig, is stunning.

It takes you through affluent, chocolate-box villages, and then the heart-lifting sight of the river and the gently folding hills beyond comes into view.

Even on a day when the frost is thick on the ground, you can't help but be moved by the beauty of the countryside.

After her morning scratch, and tempted by a handful of carrots, Winnie makes her way into the trailer.

In November, we had to find a true solution: re-home Winnie or sausage her Marianne Hill, farmer

She is a veteran of farmers' protests, and has even been to Westminster before - but pig farming is in such crisis, Winnie nearly ended up for the chop before Christmas.

"We'd lost three-quarters of the farm under the floods", says farmer Marianne Hill.

"She's not productive, and she's a huge feed eater. In November, we had to find a true solution: re-home Winnie, or" - and here she looks rather rueful - "sausage her".

In the end, Marianne couldn't bear to lose her. But feed prices have doubled in the past year - and while supermarket prices have gone up, farmers have seen very little of this increase.

In addition, farmers say, they must also abide by stricter welfare regulations than in other EU countries, making their pigs more expensive to rear.

'Rise in slaughtering'

Industry experts say it is difficult to say how many farmers are leaving the industry, because if a farmer stops production today it will take nine months before the last of his pigs leaves the unit for slaughter.

The best indication we have, other than anecdotal evidence, they say, is that sow slaughterings (ie the breeding pigs) were up by 42% (1,800 pigs a week) during the first seven weeks of this year compared with the same period last year.

You are unlikely to slaughter breeding pigs, they say, unless you are getting out of the business.

The ice is scraped off the windows, the trailer hitched up, and Winnie and Marianne are off towards the rising sun, the M4 and London.

Star of the show

Fast forward a few hours, and in her spacious London pen opposite Downing Street, Winnie's asleep.

But that hasn't stopped a small queue of MPs, men in their suits and women in brightly-coloured jackets, forming to have their picture taken with her.

Every local paper and constituency action leaflet will, no doubt feature Winnie and a smiling politician over the coming days and weeks.

The rally, about 100-strong, is a jovial affair. Renditions of Stand By Your Ham, a re-write of the Tammy Wynette song which has been recorded by the farmers, keep curious onlookers amused.

So, was it a success?

The farmers are delighted by the coverage - and that politicians of all political persuasions have come down to show their support.

"We only need 17 pence on a packet of bacon to get us back towards profitability." says Hugh Crabtree, one of the organisers.

The shadows lengthen as the afternoon draws to a close.

The rally protesters wander off to go shopping or look at the sights. Winnie's back in her trailer and back to Oxfordshire. It's been a busy day. Her owners hope that British shoppers will make it worth her while.