Gurden Theodore Thomasset was born on the 30 September 1894 in Beckenham, Kent, the son of Victor Thomasset and Julia Eulalie Thomasett (née Chapin) of 52, Queen Victoria St., London. He had a younger brother, Reginald.

He was educated at Marlborough College between 1908-1913 and was part of the school hockey XI. Gurden won a Mathematical Exhibition in December 1912 to Gonville and Caius College Cambridge studying for a First Class in the Mathematics Tripos Pt1. He continued his hockey playing in the Cambridge University Freshman's Hockey match and was also a Sergeant in the university Officer Training Corps.

His education was cut short on the outbreak of the First World War. On 26th August 1914 he was commissioned as a Second Lieutenant in the London Regiment and sent to France in March 1915 as part of the British Expeditionary Force.

Gurden was promoted to Lieutenant in the 20th Bn. London (Blackheath and Woolwich), part of the 47th (London) Division.

On 25 September 1915, his battalion took part in the Battle of Loos, detailed to follow-up an initial advance by the 1/18th London (London Irish), with objectives to the south of Loos. They were involved in hard fighting around Chalk Pit Copse and the village of Loos itself and Gurden was killed in action that day, aged 20.

His Captain said: 'He was without exception the best and most reliable officer I had and was really loved by his men and trusted by them".

He was awarded the 1914-15 Star (2/Lt), and the British War & Victory Medal (Lieut).

Gurden is buried in CWGC Loos British Cemetery in plot I.A.11. He is also commemorated by a personal memorial in St. Nicholas Church, Studland, Dorset, on the War Memorial in West Wickham, Kent and the memorial in St John the Baptist Church, West Wickham. He is also on the Roll of Honour at both Marlborough College and Caius College.