Branford Marsalis, Ronnie Scott's, London <!-- none onestar twostar threestar fourstar fivestar -->

Branford Marsalis warned recently that his quartet's music is most definitely not for children; and he wasn't just referring to the presence in his band of Jeff "Tain" Watts, a man who glowers and clatters from behind the kit like no other, and whose expressions of manic glee always remind me of Dr Kananga from the Bond film Live and Let Die.

The elder Marsalis sibling is more relaxed than his trumpeter brother, Wynton, and stylistically much more modern. But they share a deep seriousness of intent. As Branford's band explores post-bop of the heaviest kind, it means the result is not always the easiest to connect to; on their second night at Ronnie Scott's they even played a piece with a 14-bar structure. Its motif kept returning at moments that seemed odd, so accustomed is the ear to multiples of four.

That tune, however, was compelling, as was the quartet's opener, an up-tempo number in which the leader's tenor sax was as garrulous as that of Pharoah Sanders. Under this, a regular four in the bar was laid down by double bassist Eric Revis, while Watts kept the waters boiling by marking the fast swing as much with counter rhythms on the toms as with straight beats on the ride cymbal.

Pianist Joey Calderazzo, meanwhile, confined himself to a mere chord or two per bar, keeping the time and harmony anchored. They were the perfect example of a well-structured quartet.

Calderazzo was outstanding, producing solos that could have been used by students as textbook expositions of modern jazz styles, from Monk-ish plinkiness to the open fourths and fifths in the left hand that forever recall McCoy Tyner's heyday, alternating with rich double-handed block chords and fast-flowing explorations in the upper half of the piano. Neither could Revis and Watts be faulted, nor the playing of their leader.

However, for all the intensity on stage, there still seemed to be an emotional void at the heart of the music. For this the blame, if blame is the right word, has to be laid at the door of Marsalis. His tunes require work from the listener, not least because post-bop of this kind sometimes seems determined not to throw the audience too many melodic and harmonic crumbs. This is not to say that all the sound and fury of Marsalis's band signified nothing; merely that it was not always particularly easy to say precisely what it did signify.