The son of John Watson, a civil servant, he was born in Manningtree, Essex, and educated at Stirling.

His paternal uncle Rev Hiram Watson (1813-1891) was a minister of the Free Church of Scotland and John appears to have chosen to follow in his shoes.

[3] While travelling in the United States he died from blood poisoning, following a bout with tonsilitis,[4] at Mount Pleasant, Iowa.

[8] It is thought that Maclaren was the original source of the quotation "Be kind, for everyone you meet is fighting a hard battle," now widely misattributed to Plato or Philo of Alexandria.

The oldest known instance of this quotation is in the 1897 Christmas edition of The British Weekly, penned by Maclaren: "Be pitiful, for every man is fighting a hard battle.