Britain is training record numbers of workplace “mental health first aiders” to confront a sharp rise in people expressing mental distress, though evidence of success is mixed, according to a Guardian study.

Requests sent to every FTSE 100 company show that they alone have trained more than 10,000 staffers, while mid-tier and even tiny businesses are appointing first responders who can be approached confidentially by those with depression, anxiety, stress and other conditions.

A national training body, Mental Health First Aid England, said 140,000 people were trained in 2018-19 – the most ever in a single year, from local hairdressers to employees in global corporations.

Almost half a million people in Britain have now been through an MHFA programme – about one in every 100 adults.

“We have worked in more than 20,000 businesses and organisations,” said its chief executive, Simon Blake. “The exciting thing for me is that training courses are as likely to have someone from a shop in Doncaster as from a City firm.”

In terms of numbers, big firms lead the way. More than half the FTSE 100 companies have mental health first aiders (some call them “buddies”, “champions”, “advocates” or even “be well allies”). Lloyds Banking Group has a programme to train 2,500 by next year, while National Grid and Severn Trent both have more than 1,000.