oryctolagi, on 2016-February-17, 08:05, said:
I learnt a lot of my bridge back then from an excellent little handbook by Terence Reese, no less (and you're surely not about to dismiss him as a dumbass player or something....?)
In the book, he quite explicitly states "If partner has already made a bid, a double is for penalties with the expectation of defeating the contract".
Of course, I know full well that I can't play by that book any longer. Bridge has changed beyond recognition in the 50 years since, and I've had to learn my way into BBO systems the hard way, with many slip-ups on the way. I still don't understand much of plenty of other players' convention cards, even in the Acol Club. But I get by, now. And yes, I know that double of an opponents overcall at the one level no longer means penalties. After all, we have negative doubles now (which I do understand....)
So I'm wondering where we get by insulting other contributors to this forum, possibly for no other reason than that they were, like me, playing bridge a long time ago. Oh well, if someone else can be a p****, so can I.
The last time that I regularly played club bridge my partner liked to keep things very simple, so we played old fashioned penalty doubles. It proved to be very effective, catching many oppo by surprise and picking up many penalties. I'm not saying that it is the best method, but is better than playing more complex systems that aren't fully understood, as happens all the time on BBO.
It does strike me that the popular current method of playing all low level doubles for take out, with the expectation of partner reopening if you pass, just ends up exchanging the meaning of pass and double, with no real benefit.
As to the original question, double can have any of the meanings given, by agreement. However I think it depends on moe than the number of spades held. I would be less willing to double if I held support for partner, as it risks him making a penalty pass. So, without agreement, I would treat the double in the same way as a standard take out double; likely to hold four cards in an unbidden major but not guaranteed, especially if strong .