JIBDAR:
We had two T-21s in Aden; 403 and 404. We were not strictly RAFGSA but were known as the Aden Services Gliding Club. 404 was the Yellow Peril and it was indeed all yellow. Although it was part of the fleet, I believe it was owned by Shep Shepperd who was the civilian Chief of Police in Crater.
At the end of 1966, 404 was trailered down to Khormaksar from Sheik Othman for a recover and annual overhaul (as was Swallow 400). When they were finished, we decided that the security situation was too dodgy to take them back by road so we would try to fly them back.
The date was 22 January 1967 and Stu Hoy + 1 soared 404 back to base. She was then all silver with a red stripe on the top of each wing.
404 did indeed end up at Sharjah and I did some instructing there in 1970 and I last flew 404 there on 14 February 1970. At that time it was exactly as it was when it left Aden (no yellow wings).
I have two suggestions; get on to the Aden Services Gliding site on Facebook and scroll down towards the beginning where you will find some photographs that I posted on the site including 404 at Khormaksar. You will also find Yellow Peril photographs.
My second suggestion for you is to contact Stu Hoy at Anglian Sailplanes who probably knows more about 404 than the rest of us put together!