By Benedict Tetzlaff-Deas UK security experts have responded to claims that Russian cyber-hackers may have been responsible for the Greggs IT glitch that forced multiple stores to close. The IT outages yesterday prevented payments from being accepted and the issue affected branches of bakery chain nationwide, including in London, Sheffield and Birmingham. Some stores put up temporary “closed” notices on their doors, others were only able to accept cash payments. Others told customers to order outside on the Greggs mobile app before their food could be given to them. It came only a matter of ho…