[gszes]

 Tramticket, on 2018-December-20, 10:01, said:

South's hand was ♠A ♥- ♦KQ8X ♣AT9XXXXX

10 tricks was the limit of the hand - and that needed sub-optimal defence.

we can see why 4c natural (vs a spade raise) is not helpful. There is little to no way responder can judge well what to do and it takes up a huge amount of space while bypassing a (possibly) vastly more lucrative 3n for no good reason. I am closer to a 2c bid than a natural 4c bid and do not have too much heartache for 3c bidders. 2d is interesting but can lead to disastrous results if responder has a decent hand and will not keep quiet.

[nige1]

More than 50 years, ago, on a hand like this, 2 top Scottish players produced this succinct sequence.
The Sharples brothers had already established that a 4-level jump rebid promised a fit in responder's suit.
Ian and David probably didn't have that agreement but arrived at that useful understanding, by Bridge logic.

---