Titian raises the tone

When visiting Kenwood House, with its choice Old Master paintings, its Robert Adam Library and its landscaped gardens, it's hard not to agree that Guinness is good for you. This is because it was all given to the nation in 1927 by Lord Iveagh, whose vast wealth derived from having inherited the Guinness breweries in Dublin.

Clerics & Connoisseurs is a celebration of the art collecting habits of another English family who made it big in Ireland. Charles Cobbe went to Dublin as a young man in 1717, and by 1743 had become Archbishop of Dublin, the fourth most powerful political position in Ireland. It was a lucrative post, and on the proceeds he built a country house in Newbridge, just north of Dublin, which was gradually filled with paintings. His descendants continued to live there and built up the collection, and in 1985 the family opened the house to the public. Designed by the English architect James Gibbs, it is one of the finest such houses in Ireland.

The show is a mixture of family portraits and Old Masters, packed cheek-by-jowl. The highlights include a recently restored late Titian portrait of a mother and daughter. Titian's original had been overpainted by a follower and transformed into a stolid religious scene, with the mother becoming a portly winged angel. With the overpainting now removed, Titian's smouldering sensuality and loose, diaphanous brushwork can once more be marvelled at. Another powerful recent discovery is a small picture of Mary mourning the dead Christ at the foot of the cross, which has just been attributed to the great French painter Poussin. It is an intense product of his early Venetian phase.

But there is not enough high-quality work, or strength in depth, to make for a coherent exhibition. There is little evidence of passionate commitment to particular artists or schools, let alone connoisseurship. To use another beer metaphor: Clerics & Connoisseurs lacks head, and is only moderately good for you.

Kenwood House, NW3, Until 27 January (020 8348 1286).