It’s a gloriously simple idea. Put four old friends, all of them stars of stage and screen, all of them dames, together, and let them reminisce as the cameras roll. Even so, director Roger Michell could hardly have anticipated the wealth of treasurable anecdotes that would result when dames Maggie Smith, Judi Dench, Eileen Atkins and Joan Plowright got together over a wet weekend in the country. Stories of errant landladies on the rep circuit, confidences about respective husbands and delicious hints of impropriety (“We swung early, we didn’t need the 60s”, says Atkins to Dench), are cut together with diligently researched archive material from four remarkable careers. It’s wonderfully entertaining and celebratory stuff, enlivened particularly by Smith’s deadpan comic timing and Dench’s fondness for swearing like a trawlerman.