2,000ft? Pah, that's a normal good launch.
Upavon, March 1961, T21 with John Willie flying to demonstrate the technique, Taff Thomas winching.
At 3,200 or thereabouts it back released. Taff had noticed there were about 5 turns left on the drum, so let three of them out rapidly. He didn't know what would happen if it didn't back release