"Excellent formation work - much more difficult than it looks."
Oh so very true, India, I guess due to a combination of a low wing loading and low power - and Line Abreast (as shown) seems the hardest of them all. A group of Chipmunk owners here participate in a formation team; hard work, a lot of fun though we're not that good either!
Now, back to "Pongos flying Chipmunks":
Firstly, a 1993 EFTS formation. I have a personal interest here, as the rearmost Chipmunk (WG478/"L") is mine!
And another 2 FTS, Church Fenton photo. From the top the aircraft are: WP8**/"15", WG478/"20", WK507/"36", WK643/"39" and WD347/"03" (this last one is a visitor from CFS). I would date this aircraft as c.1973. Who would have thought that, nearly 40 years' later, WG478 and WK507 would be still flying and sharing a hangar on the other side of the world!