It was opening night for The Who this past Wednesday and, my oh my, Boston's rock and roll heart was all aflutter. Not since the Rolling Stones had descended upon the city in late 1969 had there been so much giddy anticipation.

And The Who, after all, were giving us three full nights at the tidy little Music Hall, not a monstrous one-nighter at the cavernous Garden such as the Stones had offered. When the tickets had gone on sale Saturday, July 6, all 13,000 of them had been gobbled up in five hours.

Actually, the grand event was eventually stretched to four nights.

Producer Don Law, who virtually introduced The Who to Boston and America when he was manager of the old Boston Tea Party, added last evening's performance when the British foursome's show in New Haven's Yale Bowl was cancelled.

Four nights! Outside the Music Hall on Wednesday, the air was fairly crackling. Security was tighter than it has ever been for an indoor rock show in Boston, with police and guards patrolling the sidestreets and alleys looking for crashers. Reaching the stage door took some doing.

Once inside, however, the backstage atmosphere was subdued. Those who had been predicting high revelry in the wings similar to that which accompanied, say, a recent Faces concert at the Music Hall, were wrong.

For one thing, an order has descended from room 222 at the Holiday Inn on Blossom Street, where Peter Townshend, the Who's mercurial guitarist and image figure, was sequestered.

He had ordered a "press ban" for opening night, not only in the group's dressing room, but also anywhere backstage. Thus when The Who's rented limousine edged through the light rain at 8:30 ("A bit late, we overslept," explained singer Roger Daltry), Townshend did not have to face the journalistic barrage for which he has never expressed any love.

Instead, the four went unimpeded to their lime green quarters below the stage, where a bright orange table offered hors d'oeuvres, sandwiches and all manner of drink. There they talked quietly, reluctantly received a few visitors and waited to go on.

It was road manager John Wolfe, a man with a reputation for toughness, who acted as father protector. Looking with his shaved head for all the world like a Prussian general, he was everywhere during the concert, first roaming behind the seven and one-half tons of equipment giving orders to the sound men, then running into the audience to command security guards.

At showtime, The Who marched quickly onstage, and quickly off two hours later. As the audience of 4302 screamed for an encore, they trooped down the stairs to their dressing room, then up again for a crashing finale.

No, there were no outlandish festivities for the long-awaited event, only backstage remoteness and on-stage concentration.

Except once. During the thundering encore, John Wolfe was alone behind the wall of amps. But this time he was not giving orders. He was dancing.