For Briton John Field, a custom-made uniform is the most important part of the job (the beard and belly — also crucial requirements — are natural). Otherwise, he wouldn't be Father Christmas.

Actor John Field, dressed as Santa Claus, at a Christmas grotto at the Wetland Centre in west London, Dec. 5, 2015. | (REUTERS/Stefan Wermuth)

Field, 66, a former teacher turned actor, has stepped into the jolly role of Santa for more than 12 years. "I'm playing a part, but it is one of the most truthful parts I can play," he told Reuters. For about a month every year, Fields dons his bright red uniform and stations himself at a few outposts around London, including a charming wood grotto in the pine forest of the city's Wetland reserve, and inside the sightseeing boats that putter up and down the River Thames.

Thousands of children will visit Field during the holiday season and he'll gamely listen to their wishes, read their letters, and tell them classic Christmas tales. Despite the challenges posed by the occasional crying or sick kid, Field said he's committed to sharing the magic of the season. "Being a Father Christmas you have to make an agreement, a non-written agreement with both the parent and the child: to believe."

Below follow Field, during last year's holiday season, as he transforms into Father Christmas and spreads holiday cheer around London:

A girl peeks through the doors at the Christmas grotto. | (REUTERS/Stefan Wermuth)

John Field brushes his beard as he dresses as Santa Claus before a performance on a City Cruises boat on the River Thames. | (REUTERS/Stefan Wermuth)

(REUTERS/Stefan Wermuth)

Parents and their children line up at the Wetland Centre. | (REUTERS/Stefan Wermuth)

(REUTERS/Stefan Wermuth)

(REUTERS/Stefan Wermuth)

John Field reads to children on a City Cruises boat. | (REUTERS/Stefan Wermuth)

(REUTERS/Stefan Wermuth)

John Field rests between performances on a City Cruises boat. | (REUTERS/Stefan Wermuth)