Music: SIR EDWARD HEATH CONDUCTS Kenwood House, London

Hampstead Heath meets Sir Edward Heath. What could be more appropriate than for a 79-year-old ex-prime minister in search of a birthday party to inveigle 9,000 people into watching him having fun. You have to hand it to him: Sir Edward's certainly got a few more strings to his bow than the current PM. No need for soapboxes here because our fun-loving sailor has got his podium. And this owner of 3,000 CDs has clearly been conducting along in the privacy of his own quadrophonically enabled drawing-room so as to prepare for his Big Night.

The Lakeside concerts at Kenwood House have long been an institution. An idyllic pastoral setting in the open air. An excuse to pack the hamper. London's answer to Glyndebourne set among the Glyndebourne-going classes, but without the need to dress up. British gentility in tune with itself.

But what's this? "Ranieri, Britvic and Bacardi welcome you to sample their products throughout the evening..." "English Heritage invites you to become a member." "CDs and cassettes of Sir Edward's favourite music signed by tonight's conductor are on sale..." (No matter that the CDs and cassettes are not conducted by tonight's conductor - a minor detail - but spare a thought for Sir Charles Groves squirming in his grave.)

For Kenwood concerts, these days, have become seriously challenged marketing opportunities. Well, I've always thought that out-door concerts were a bit of a contradiction in terms. In my student days, concerts at the out- door summer home of the Chicago Symphony were more a succession of screams from babies and jet engines than much to do with music, and even at Tanglewood, the Boston Symphony's summer location, the music was always hard to hear.

In Hampstead, engine and baby noise is somewhat reduced by heavy "assistance" from an amplification system that seems to function on the reverse limiter principle - when the music gets soft, the volume goes up. But the audience isn't too bothered, applauding at will with little concern that "mixing and matching" the sound is out of the conductor's hands.

Which leaves little for a conductor to do, except keep the players together and try to keep up with them - not something at which Sir Edward was entirely successful, judging from moments of frantic rival conducting emanating from the English Sinfonia's gallant lady leader.

The programme of Sir Edward's "favourites" included pastoral music for a pastoral setting - Elgar's Serenade, Delius's The Walk to the Paradise Garden (substituted for the possibly more appropriate Wasps overture by Vaughan Williams), Bruch's Elgarian Violin Concerto with Vasko Vassilev, Beethoven No 8 - all movements in roughly the same tempo - and, to round things off, Elgar's Pomp and Circumstance march, complete with "bang"- coordinated fireworks.

With midget-sized musicians waving about like crazed insects in the far distance, and musical standards so low, can it be long before the live orchestra is dumped for pure, electronically pumped muzak - and would anyone in the Kenwood audience mind, apart from Sir Edward?