Andi,
I was speaking with one of your ex-colleagues over the weekend who use to do the Derby Road Trip working. I didn't ask how the trains got to the sidings from the Ipswich End, but from the description he gave me for the run-round operation after shunting into the scrap yard; I would imagine it would come straight into the up platform the wrong way; otherwise to use the run round loop would require the issuing of a token to Trimley and a long round trip to give it up!
Now to get the loco from the Felixstowe end of the train to the Ipswich end after shunting the scrap wagons required some fly shunting. So the driver (normally a on a 47) would accelerate like hell towards the two sidings, then after a signal was given by the shunter he would put the brakes on, but still with the throttle open. This would cause the wagons to buffer up and the shunter could then unhook them using his pole all while still on the move; the driver would then accelerate away from the wagons, once the loco had cleared the point the shunter would throw it and the wagons would run into the siding parallel to the one the loco was in. Hence it was then possible to get to the Ipswich end of the train.
He didn't give me the date for when this was being done, but a guess it would be around the mid-eighties.
Regards
Kevin