"I'm not competing with the Rolling Stones, you know," singer Roger Whittaker said with a chuckle. He then launched into a version of "Hound Dog" that would have sent some of his younger pop counterparts straight to the showers.

Whittaker's concert last night at the Constitution Hall was a demonstration of pop music in all of its guises. At its worst it bordered on the banal, one step above Muzak and one below a Mitch Miller sing-along. Fortunately, it also had its moments of unabashed joy and emotion.

The Kenyan-born singer's performance traversed a staggering variety of styles -- a Zulu mating song, Welsh and Scottish ballads, calypso numbers, American love songs and rock 'n roll were all included. some of his selections were reduced to a kind of pop gloppiness (most notably, his rendition of a traditional English folk song). Yet others were given sensitive readings. John Lennon's "Imagine" was particularly moving.

Throughout, Whittaker displayed a remarkably clean and refined vocal style. His show-stopper, however, proved to be his whistling -- fleeting and precise phrases were delivered with uncanny skill. He is surely the Rampal of whistlers. Most of all Roger Whittaker is an entertainer of the first order. At times, he may have seemed behind the times, but at others he was timeless.