British workers spend £5.5b on shop-bought lunches each year while leaving almost the same value of food at home to waste, according to a study.

Ham, bread, cheese, cold meats and other typical lunchbox foods such as fruit, crisps and yoghurts are binned to the cost of £5.06bn every year, the survey for the Love Food Hate Waste campaign found.

It revealed 2.1 million tonnes of food suitable for a packed lunch goes to landfill each year, including £821m worth of breads (530,000 tonnes) and £94m worth of sliced meats (23,000 tonnes).

However, the research found that 28 per cent of workers never prepare lunch from home, while 33 per cent take lunch to work every day.

Love Food Hate Waste spokeswoman Julia Falcon said: “There’s obviously a move by some of us to save money and bring lunch to work, and this new survey shows that some of us could be saving up to as much as £120 each to spend at Christmas if we start free lunching now.

“Most of the time there's a packed lunch waiting in the fridge if only we noticed it, and there really is such a thing as a free lunch when you take last night’s leftovers with you."

More than 80 per cent of British workers have access to a microwave and 86 per cent to a fridge at the office, but just one in five uses up leftovers for lunch, the research found.