By JILL LAWLESS
LONDON (AP) — The U.K. is celebrating the 75th birthday of its beloved but increasingly creaky National Health Service. The date is being marked with charity tea parties, royal visits and a service of thanksgiving at London’s Westminster Abbey. However, three respected health think tanks warned Wednesday that the NHS is “in critical condition” and won’t make it to 100 without more money and better long-term planning. The anniversary comes as backlogs, treatment delays, funding gaps and an unhappy workforce create an increasingly threadbare and overstretched system. The health care systems of other countries with aging populations are under pressure following the coronavirus pandemic. But years of government austerity and Brexit have made the NHS’s problems particularly acute.