Bosses at sandwich chain Pret A Manger have said they have to “start asking questions” about the use of plastic and paper in packaging.

Staff are offering a booklet to customers which raises a number of environmental issues.

The booklet says “lots more” needs to be done.

One section headed “This is rubbish” lists a series of “what if…?” questions.

“We have to start asking questions… all starting with ‘What if…’,” says the booklet.

“What if… we had drinking taps in every shop?

“We had a return deposit on all Pret plastic bottles?

“We used less paper and plastic in our packaging?

“We used more recycled content everywhere?

“We stopped selling plastic water bottles.

“We made our coffee counters out of old coffee grounds?

“We used cups and trays made from old cups (and trays)?

“All of our packaging was compostable.”

The booklet adds: “There’s lots, lots more we need to do.”

Pret offers a 50p refund to customers who bring a reusable coffee cup and earlier this year chief executive Clive Schlee announced a trial of a deposit scheme on Pret plastic bottles.