The tour group, which included representatives from the City of London Corporation, met with traders who had formed partnerships with growers as a result of the scheme.
They included Clifford Hart, who sells British asparagus after the BDM programme helped the grower to promote his product more effectively.
Hart said: "If you put a Union Jack on a product it is amazing the difference it makes."
Paice also met trader Ronny Liu, who reported that English garlic roots flew off the shelves in two hours after he started supplying them.
Liu is also selling apple juice from a Herefordshire grower after Williams helped the grower devise a business plan.
Williams told Paice: "We started the business from nothing, but have created jobs and hope to export juice by this time next year."