I did have some faded and fuzzy memories of Luther but as he walked on stage he wasn't quite as I imagined.
And after two or three numbers my consternation multiplied. To be blunt, he didn't seem himself.
As always, my instincts proved correct, because Luther Vandross was dead. And still is.
The penny dropped when I was asked how he matched up to the "real thing".
It was a tribute act, and the singer's name was actually Harry. For the record it was Luther UK, and they were excellent.
Tribute acts can indeed be very good, but you can't get away from the fact that putting someone in a wig doesn't make them Agnetha, nor does a hairy chest a Freddie make.
So I feel, just slightly, for Conservative Party members at the moment who voted during the summer for what they believed was a Margaret Thatcher tribute act.
If you half close your eyes and listen to the voice you could convince yourself that Liz Truss is Mrs T.
Those younger party members who were not even alive when Mrs T was in power were basing their voting decision on the legend, fairy tales and folklore.
One of Mrs Thatcher's greatest hits, of which we have heard a lot this week, was "U turn if you want to, the lady's not for turning".
In her mangled cover version, Liz got the words all mixed up and it has come across as a political hokey cokey.
As a matter of fact, the idea that Margaret Thatcher would stick to her guns regardless is all part of the Maggie mythology.
Remember the time when she cravenly caved in to the miners? Probably not, as it doesn't conform to the conventional Maggie storyline which focusses on 1984. But it's true.
In 1981 Mrs Thatcher's government planned to close 23 coal mines. These days such a move would be greeted by wild cheering from the green lobby.
They would see it as a positive step away from planet-destroying fossil fuels and a chance to redeploy miners from their dirty, dangerous, and environmentally-unfriendly toils and give them jobs in the agrarian industry or retrain them in IT so they could change the plugs of early 1980s computers.
But back in the 1980s nobody thought like that about miners, who were popular heroes, and coal was considered by the public a strategic resource even though in reality everybody was moving to gas-fired central heating.
In the face of the planned closures the miners threatened to strike, and there were some unofficial stoppages.
Margaret Thatcher backed down and did a U turn. So the lady was for turning after all.
Liz Truss's speech to the Conservative Party conference this week was a success, albeit with a low bar for success in the context of current circumstances. The criterion for success was that she did not say anything that made things worse.
It was a get-me-through-this-without-fouling-up speech. Despite the clapping and the ovations, she did not come across like a real leader, but as somebody trying to be a real leader.
Boris Johnson has also left poor Liz in an unhappy position. Seeing what became of him, she has apparently committed herself to give clear and truthful answers to direct questions.
So when asked if the plans to cut the top rate of tax were discussed in advance by full Cabinet, she hesitated for just a moment before coming out with a full cough, and admitting: "No, no we didn’t. It was a decision that the Chancellor made."
Her response was considered politically naive, as well as throwing her Chancellor under the bus which, given their conference love-in, wasn't what she intended.
This is the underlying hypocrisy of the trust-in-politicians gimmick. If a politician tells the truth, they are often liable to get slaughtered for it. The political game is dodging an uncomfortable truth in a manner which is not an outright lie.
Boris Johnson, who was always an outsider in the Palace of Westminster, never bothered playing that political game.
Liz Truss has a couple of years to flourish and grow into the role of leader. But at the moment, like that Luther Vandross tribute act, she doesn't quite convince as the real thing.