BROZEL
Overcalling 1NT: An Overview
Dble = 1 suiter (partner takes out to 2♣).
2♣ = Clubs and Hearts.
2♦ = Diamonds and Hearts.
2♥ = Hearts and Spades.
2♠ = Spades and an unspecified minor.
2NT = The minors.
Dble = Penalty (of dubious value vs a strong 1NT).
2♣ = Any 1-suiter (Advancer bids 2♦ to ask).
2♦ = The majors.
2♥ = Hearts and a minor.
2♠ = Spades and a minor.
2NT = The minors.
Dble = Any 1-suiter (partner takes out to 2♣).
2♣ = Clubs and any higher ranked suit.
2♦ = Diamonds and any higher ranked suit.
2♥ = The majors.
2♠ = Spades ONLY, weak (else 2♣, then 2♠).
Brozel is an old but excellent way to compete over a Strong 1NT opening. Yes, people use it against a Weak 1NT opening too, but it is less effective there.
Partner ("Advancer") can bid 2♣ to ask for which suit Doubler has, allowing Doubler to Pass if hir suit is Clubs.
In this regard, Brozel works exactly as DONT does.
Cappelletti, which uses 2♣ for all 1-suiters, is inferior in that Advancer must bid 2♦ to ask for the suit and, if Doubler's suit is Clubs, the pair is forced to 3♣ (too dangerous over a strong 1NT).
Note that Overcaller is bidding one of the suits s/he owns, which makes it tough for Responder to double you.
Also note that Advancer does NOT have to guess which suits you have and can pass Clubs at the 2 level.
Again, this is superior to CAPP, which bids 2♥ with this hand, showing Hearts and an unspecified minor. CAPP Advancer must bid 2NT to ask for the minor and will NOT be able to stop in 2♣.
It is slightly superior to DONT, which uses 2♣ to show Clubs and any 2nd suit. DONT Advancer might go "fishing" for the 2nd suit with 2♦, only to be disappointed and want to retreat to 3♣.
Again, it has the advantage of bidding a suit that you do have, and allows partner to pass at the 2-level.
Again, this is vastly superior to CAPP and slightly better to DONT.
It has the advantage of bidding one of your suits, but this may become a disadvantage against a Weak 1NT, if you have a very good hand and may be able to make 4♥; partner is liable to pass 2♥. :(
In CAPP, 2♦ shows both majors, guaranteeing that
Overcaller can rebid (an important consideration
over a weak 1NT, when we may have game !).
This is dangerous over a strong 1NT, since it gives
Responder a "free" double of 2♦ on virtually
any 8 HCPs, possibly landing us in trouble.
That Responder might NOT be able to double 2♥
unilaterally — especially if Responder has very
few Hearts.
Note: this is the only 2-level suit-overcall that does NOT show Hearts !
This treatment is identical to CAPP's, but may be slightly inferior to DONT in that the pair cannot stop in TWO of the minor.
This is consistent with most overcalling systems Other than DONT, which can stop in 2-of-a-either minor by overcalling 2♣ (Clubs and a minor).
All in all, Brozel is a very effective choice over a strong 1NT. It is a marginal choice over a weak 1NT opening. Of the universally recognized choices (e.g., CAPP, DONT, BROZEL, ASTRO, etc.) it is arguably the best choice available due to its speed of disclosure, natural approach and relative simplicity. Indeed, only the Geneva Convention ("McGuinty") beats it, and Geneva is unknown outside of central Canada. :(