There’s always a moment in ZZ Top gig when Billy Gibbons steps up to the microphone and says: “are we having a good time…”

It never feels like a question. More a re-enforcement of what everyone understands.

That is even more the case than usual, tonight as Messrs Gibbons, Hill and Beard are celebrating their 50th Anniversary.

In truth, they are doing it in much the same way they do every other gig they play: that is to say, with an hour and 20 minutes of the music that is unmistakably ZZ Top.

After half a century, there’s bound to be an element of routine about it and there’s a bit of the thought that you know what’s coming next throughout.

Largely because, if you’ve seen the band in the last decade then, literally, you have seen this before.

From “Got Me Under Pressure” at 9pm to “Jailhouse Rock” 80 minutes later the Best Little Old Band From Texas are slick, professional and have a collection of some of the greatest songs ever made.

If you want to fill arenas on your 50th birthday then you’d best have “Jesus Just Left Chicago” In you’re top hat too, and “Gimmie All Your Lovin’” would help and so it goes.

There’s some other moments that always happen in ZZ Top gigs too. The bit where you realise just how fabulous a guitar player Gibbons is comes in “Beer Drinkere And Hell Raisers” and the bit where you remember just how brilliant the “La Futura” album was comes when “I Gotsta Get Paid” happens.

The set – as always – ends with “Sharp Dressed Man” And “Legs” (and if you had two of the biggest and best rock n roll singles ever you’d get your furry guitar out and crack on, wouldn’t you?).

Then they come back with those sparkly jackets and calmly pull out their two best. “Play that thing, Billy!” Growls Dusty Hill and “La Grange” does well, it’s thing. It’s better than your thing too. As is “Tush” and yeah, you’re allowed a second encore when you’ve achieved this status and “Jailhouse Rock” is a party not just at the county jail.

The thing is ZZ Top know what they’re doing, and to paraphrase Lemmy, they do it real well.

Other bands can take chances. ZZ Top are bad and nationwide for this long because they’ve got a magic formula.