Pret a Manger has brought back its co-founder in a boardroom shakeup at the coffee chain, as it grapples with tech chaos sparked by a revamp of its subscription service. Sinclair Beecham, who co-founded the sandwich and coffee business with Julian Metcalfe in 1986, will return in a bid to help the chain “reaffirm Pret’s mission” to focus on customers. Mr Beecham and Mr Metcalfe opened their first Pret store on London’s Victoria Street after buying the name and assets from a collapsed coffee shop. The store sold sandwiches and meals made on site, contrasting with what Mr Metcalfe has previously called “very grim” options for takeaway dining at the time. The return of Mr Beecham to Pret comes amid anger from customers over a major change in Pret’s popular subscription service, enacted to crack down on a loophole that allowed users to share free coffees with friends and colleagues. The chain began forcing customers using its subscription service, which offers five hot drinks per day for a monthly fee of £30, to log in through its app earlier this year. However, since the change, customers have run into technical difficulties, while those without smartphones have been effectively locked out...