Sorry I doubted your advice there Ned! I just didn't spend much time with bicycles in the 80's, trying to fill the gaps now.
I didn't realise you had doubted it so no worries!
I never had a frame with the drillings myself. Colin Lewis Cycles were selling the levers and frame fitting for 'nowt' in the mid 80's so I bought a set to use the levers on a winter bike. They were like a normal DT lever but had a small extra 'ratchet clip' underneath which, when moved, allowed the lever to go further 'forward' than normal allowing the gear mech to derail onto the frame fitting. The wheel could then be removed with the chain still in place, ready to go back onto the sprockets easily. The frame part got chucked in the scrap box. Now it's the only part I have as the bike was sold with the levers on it.
Today is the yesterday of tomorrow.