More than 30 years after Raymond Briggs’ story became a stage show, director Will Tuckett and Paddington designer Tahra Zafar have given it a hi-tech refresh with a hunky Saint Nick “Top of the show!” says Will Tuckett. On the grand piano, musical director Andy Massey strikes up an arpeggio that could melt the most frozen of hearts: “We’re walking in the air …” It is The Snowman, of course. Raymo…