Like father, like son

The tickle of Tango

"From the Temple of Heaven (Park) to Taoranting Park to Xuanwu Park and then to here, finally," recalls Gong, with a beam of triumph. "I've always been following them. It's been eight years."

So has Liu Yan, 52, a healthy young retiree from a post office, who enjoys dancing in front of a big crowd. "I always come here an hour earlier, just to give them a hand," Liu says. "Mrs Zhou sometimes gets sick. She really needs our support."

Other than the 30 core members of the choir, Zhou and Bao do not keep personal contacts or records of the approximately 1,000 participants.

The choir may be more likely to grow than to shrink: Beijing's elderly population is growing rapidly, with 400 people reaching the age of 60 every day, according to a report by the city government. In 2012 the total number of registered Beijing residents was 12.98 million, of which nearly 2.63 million were 60 or older, the report said.

After half a day's performance, the couple tidies up and packs their things before heading to a small canteen nearby for dumplings as a treat.

"Of course we have thought of giving up. We've thought about that quite a few times. My wife is not in good health. She had fever again this morning," says Bao on a gusty winter morning when temperature fell well below freezing. "But every time I saw my retired friends' happy faces, I'd say to my wife, 'this is worth it!' "

Chen Mengwei contributed to the story.