keithhus, on 2015-January-14, 11:26, said:
Hi, I am a beginner (wishing to learn) and from my teaching I would bid 1NT - ie. 9-12, balanced, no support for partner, stopper in Ops suit. Any advice would be appreciated. I am learning ACOL in the UK.
responding 1NT to an overcall shows more than it would if you were responding to an opening bid (6-9/10). this is because overcalls are made on lower ranges (you don't need anywhere close to 12 points to overcall and with 18/19+ you normally start with a takeout double and then introduce your suit on the second round). as such a 1NT response to an overcall is normally a good 7-12 or so.
however, when the overcall is in the passout position as in the original post, the overcall can be far weaker as partner needs to protect your hand. you might have a relatively strong hand which had no suitable call (12 is ok, but you could easily have 14 or 15. maybe more if you had a lot of RHO's suit and hoped to get a penalty). as the overcall now has an even lower range, so the responses change too. a basic principle for bidding after a passout position call is 'transferred king', which means you in the direct seat pretend you have 3 points less and bid accordingly, and partner who protected has 3 points more. your 12 count perforce becomes a 9 count and you respond 1NT.
by the way, if you plan to play more online than face to face in clubs, dump acol and play some sort of 5 major system. also if you happen to be in london 5 card majors are normal enough anyway. aside from not being very good, acol has very little published material, because it's hardly played anywhere outside the lower echelons of UK based bridge.