Defiants were also used for "special" work including tactical evaluations with the RAF Gunnery Research Unit and the Air Fighting Development Unit (AFDU) at Farnborough. Two Defiants were issued for ejection seat development work: one to R Malcolm Ltd (later ML Aviation) and the other to Martin-Baker. On 11 December 1944, Defiant "DR944" was delivered to Martin-Baker's facility at Denham; sometime thereafter, a primitive ejector seat was fitted into the observers position for trial purposes. On 11 May 1945, Martin-Baker used "DR944" to test their first ejection seat with dummy launches. Various trials using "DR944" took place until May 1948. The other Defiant, "AA292", was delivered to R Malcolm Ltd at White Waltham Airfield on 15 April 1945 and the first airborne trial with dummies was held in the following October.