By graham.newton@granthamjournal.co.uk (Graham Newton) Grantham u3a has celebrated its 21st anniversary in the town with the planting of a tree. The ceremony took place in Dysart Park in Grantham. Chairman of Grantham u3a Steve Potts said: “We have much to be grateful for to those with the foresight to establish a u3a in the district in 2001 and it is right that we should celebrate that by planting this tree. “So many retired people have benefited from the organisation over the years, and today’s membership continues to enjoy their legacy.” The u3a movement brings together retired and semi-ret…