Manor Fresh has posted a 15.5% increase in pre-tax profits after increasing sales volumes of UK-grown potatoes as well as exclusive ­potato and carrot ­varieties.

Pre-tax profits at Manor Fresh which is M&S's sole potato supplier and also supplies organic vegetables to Morrisons increased to £1.46m in the 53 weeks to 1 May 2010, according to results filed at Companies House this week. Turnover rose 1.63% to £56.1m.

The company had experienced a disappointing start to its financial year, characterised by low sales of Jerseys, the directors said in their report. However, good supply of UK crop had provided opportunities to increase volume.

Exclusive supply deals, under which Manor Fresh provides a certain variety of potato or carrot to one retailer, had "advanced" and it had extended the harvesting period of UK-grown ­potatoes, reducing dependence on imports.