Brexit will be a “tough gig for all concerned” in food to go, but continuous innovation will drive growth in the sector, according to industry bosses.

Speaking at the IGD’s conference in London this week, Spar managing director Debbie Robinson said the volatile nature of the price of butter, which has risen by 93% since the EU Referendum vote, was clear evidence that challenges lay ahead for the industry.

However, she said the sector is in a good place to fight these challenges. “People come from all over the world to see what we do in the UK. We should be proud of that,” she said at the IGD’s food to go conference this week.

The IGD predicts the food to go market will be worth £21.7bn by 2021, up from £16.1bn this year. Its added food to go sales at convenience, forecourts and other retailers are forecast to be worth £3.3bn in five years’ time.

Patrick Coveney, chief executive of manufacturer Greencore, said the sector has grown by 2.3% – twice as fast as the normal grocery market. “It’s possible to make a lot of money in food to go. Growth generates cash, which isn’t the same with other industries,” he said.

Mike Abselom, BP UK trading director, said its biggest challenge as a business was to make customers return and make a trip to BP “habitual”.

He said “75% of shoppers have already decided” what they want before they enter the store, and sales of food had to be completed within 90 seconds if they are to become repeat customers.

He added it has sold 500,000 West Cornwall pasties in 10 months.

Meanwhile, Stuart Forder, M&S trading director, said the rise of gluten-free has been felt in their stores, with its Made Without range making the retailer £500,000 a week, a rate he admits M&S “can’t keep up” with.