Reginald was born in Widford, Hertfordshire on 21 August 1889, the 2nd son of James and Elizabeth (nee Haggar) Clark at Widford, Hertfordshire. By 1901 they were living in Ashwell, Hertfordshire where Reginald was a pupil at the Merchant Taylors School.
Harry was the fourth and youngest son of Alfred and Hannah (nee Chamberlain) Ingrey, born on 23 October 1897 at Bassingbourn, Cambridgeshire. He was a pupil at the Merchant Taylors School in Ashwell, Hertfordshire.
Frederick was the third son of John and Martha (nee Scoot) Sheldrick, born at Thriplow, Cambridgeshire on 12 October 1886. He was a pupil at the Merchant Taylor School in Ashwell, Hertfordshire.