When it comes to the NHS, there’s one area we all seem to agree on: a need for the health service to be efficient. And as the service turns 70, that concern is more urgent than ever.

But where most of us confine our frustration to moaning about waste in the system, Sarah Caulfield, a primary school administrator from Tenterden, Kent, has taken action – inspired by a newspaper article.

“Eight years ago,” says Caulfield, 47, who lives with Terry Collette, a 61-year-old consultant in mergers and acquisitions, “I read about the ridiculous inflated prices the NHS pays for basic orthopaedic equipment and it really stuck with me.

“The idea that a basic screw costs pennies in B&Q but nearly £100 to an NHS Trust was both ridiculous and abhorrent. There had to be a better way.”

The need for change is obvious: in November 2015 the government set the NHS a target to achieve savings of £22 billion by 2020/21, which some trusts are struggling to meet.