Writing News: By The Sea had accumulated almost 39,000 words by the beginning of this week, before I got to a suitable pause and edited it down to around 37,000. I now think I’m about a quarter of the way through, the projected length slightly less than I’d originally thought (which is a relief).

However, there’s a problem. Several characters, just ciphers in my planning document, are now more fleshed out than I thought they’d be, and I’ll need to do more with them than I first thought. So I shall have to go back and edit the planning document slightly, giving these people a little more to do, before getting back into full-on writing mode.

The Sigil, meanwhile: well, my agent tells me that it’s being sent to publishers, but is coy about anything more specific.

Meanwhile, it was my birthday a couple of weeks back, and for my birthday treat I eschewed jelly and balloons (I am 45) and instead hied off to Wembley Arena with another old rocker pal and saw Deep Purple, supported by Thin Lizzy and Styx. Now, I don’t give a tuppeny-halfpenny damn for those among you who might scoff at such old fartdom. It was a fantastic concert from beginning to end, and had you bothered to turn up you’d never have got in, and if you had, you’d have witnessed the full majesty of rock, the mystery of roll.

What occurred to me, however, was that as I’d enjoyed all three bands since my student days (and Deep Purple since my early teens), the acts on stage were even older than I was. Many of the key players in the bands as originally conceived have since died of rock’n’roll excess, or — believe it or not — retired.

Consider. It is hard to imagine Thin Lizzy without their driving force, the charismatic bassist and lead singer Phil Lynott. He died of R’n’R excess many years ago, yet Lizzy rocks on with Lynott-era guitarists Scott Gorham and John Sykes. Sykes takes lead vocal, and gets Lynott’s Dublin accent to a tee. (If you closed your eyes, I swear…) Yet none of the members of the anthemic Lizzy I saw on stage were in the original late 1960s line-up.

As for Styx, the original line-up were two brothers who conceived the band in a basement in Chicago. One died a long time ago: the other, ageing and ill, comes and does a few numbers when he can. He did so at Wembley, but he seems far away, a guest performer with a band that is now far more capable than he is.

The mighty Purple has had more line-up changes than most of us have had hot dinners. Replacement guitarist Steve Morse has now been in Purple longer than the iconic Ritchie Blackmore, inventor of that irritating riff to Smoke On The Water, banned from guitar shops throughout the land. Magisterial organist Jon Lord retired a couple of years back (he’s 66) to be replaced by journeyman Don Airey: you wouldn’t know the difference, such is Airey’s remarkable imitation of the once-inimitable Lord. Singer Ian Gillan (62) still manages the screams that shot him to stardom in Jesus Christ Superstar when I was a tiny tot – though with an effort.

The only truly original Purple, who has played on every Purple record since Shades of Deep Purple back in 1967, is drummer Ian Paice who, a mere baby of 59, looks like Benny Hill on uppers.

Yes, each one of these groups, battle-scarred, much patched, reconstituted and reformed, played with the competence of age and (it has to be said) remarkable energy. But in a sense each has become its own tribute band. Styx and Purple played new-ish material: Lizzy’s songs were all Lynott-era numbers at least thirty years old.

But the same can be said of the listeners. What with the turnover of material in my body, I am, literally, not the same person who at 14 was electrified by Deep Purple In Rock; at 17 first heard Lizzy’s Live and Dangerous or at 19 discovered Styx’s Pieces of Eight.

So the question of whether any of these bands is ‘really’ Lizzy, Styx or Purple (subject of many boring rockerish pub discussions) is the same as whether I am the same ‘me’ that I was in my youth.

Avoiding discussions of Cartesian dualism, the answer, for all practical purposes, is an emphatic ‘yes’. The continuity is all that matters, and when Purple thundered into Black Night (in the Top Ten in 1972), I was nineteen again and wearing a stinky denim cutoff. If they say that nostalgia isn’t what it used to be, they are wrong. It is getting better all the time.

PS: the best present you can get for an ageing rocker is more links for his bullet belt…