On a sunny day in the first week in August, British Baker went to visit a farm in West Sussex, one of the many to supply Warburtons with wheat, to find out more about the seed-to-crumb process.

Bignor Farm is tucked away in a picturesque setting at the foot of the South Downs, and grows a range of arable crops, including 200ha of the winter wheat varieties Hereward and Solstice, which it supplies to the plant bread manufacturer.

As well as supplying UK markets, the family-owned business, run by Tom and William Tupper, also exports from Shoreham and Southampton, and Tom Tupper welcomes the sight of greater availability of Warburtons’ products in the south of England, since the opening of the Bristol plant operational since December 2008.

Tupper, who is also West Sussex County chairman of the National Farmers’ Union, has been working with Warburtons for around nine years. The farm is part of OpenField, a farmer-owned business and the UK’s largest grain exporter. Its aim is to maximise value for all in the supply chain by securing long-term business stability for UK farmers and customers alike, through marketing and logistical innovation.

Warburtons works with around 320 farmers that all grow Hereward and Solstice wheat to a unique specification, explains Warburtons’ purchasing director Bob Beard. He adds that the founding fathers of the bakery business had a relationship with UK growers a trend which has seen the firm sourcing more and more wheat from the UK over recent years.

"We work with OpenField for security of supply, quality and provenance, but the wheat is all grown in the Warburtons way. It’s about balancing what we do in the UK with our supplies from Canada," says Beard. "We’ve got new wheat varieties that we’re looking at, which we hope will outperform Hereward and Solstice, and we’ve got a plan with Tom for the next 10 years."

Taking us to a field of Hereward itself, Tupper explains the process the wheat goes through before it ends up in a loaf of bread. "The sure-fire sign of when the wheat is ready to be harvested is when the ears of the wheat have tipped over," he says.

The bottom grains at the stock end tend to be the least ripe and he needs to know the moisture content before harvesting. It is then combine-harvested at 24% moisture and dried twice. Warburtons’ target protein level is 12-13%, with a minimum Hagberg falling number of 250.

Tupper explains that key factors in terms of establishing the quality of the wheat, are the level of protein and the Hagberg number, because if the wheat gets too damp, it germinates and becomes nothing better than low-grade feed wheat. Hereward is a premium milling wheat, but doesn’t hold on to its Hagberg falling number "it’s the most delicate wheat we grow," says Tupper whereas Solstice, a slightly thinner crop, but with bigger ears of wheat than Hereward, holds on to it for longer.

There are approximately three-and-a-half tonnes of wheat per acre and, at harvest time, the farm’s single combine is capable of harvesting 110 acres a day. Last year, the farm supplied over 600 tonnes of wheat and, this year, is contracted to supply around 455 tonnes, which Beard says is enough to keep one of the machines at the factory going for only 24 hours straight, such is the level of production at the site.

"Hereward is the best UK bread-making wheat available," says Beard. "But we’re always looking to find other wheats that perform ever better. To bakers, the most important thing is consistency."