[1] In the early 1960s the RAF issued a requirement to replace the current wooden gliders used by the Air Training Corps with a new tandem two-seater.

[1] Slingsby took the opportunity to design a new glider that would meet the needs of the ATC and could be used by civil gliding clubs.

[1] To gain experience the company purchased a kit of the Schweizer 2-22, which was then constructed to learn the techniques applicable to metal gliders.

[2] The order was cancelled following evaluation and the disruption caused when the Slingsby factory was destroyed by fire in November 1968.

Following the fire, Slingsby built a small batch of modified T.53B aircraft, the Phoenix, for the civil market, and later sold the rights of the design to Yorkshire Sailplanes which then resumed production as the Yorkshire Sailplanes YS-53 Sovereign.