The C&C Gazetteer has the units at Biggin Hill as 39(HD) Sqn. D Flt from 1/12/17 to 11.12.17. when it was transferred to 78(HD) Sqn. D Flt. until it was absorbed by 141(HD) Sqn. 9.2.18. Jefford in ‘RAF Squadrons’ (2nd Edition) has aircraft types on the strength of No. 39 Sqn including BE1, BE12a and BE2e with Bristol Fighters joining the unit in December 1917. No. 78 Sqn. has 1 1/2 Strutter, BE12b and Camels in the period concerned. These types may not all have been with D Flt of course. No. 141 Sqn. had BE12, BE12b, Dolphin, Pup and BE2e on strength during the period before Bristol Fighters arrived from March 1918.