SEVEN months ago, on his last performing visit to Glasgow, Elvis Costello was pretty sure about the basic structure of his live show. Accompanied on piano by long-time accomplice Steve Nieve, Elvis would simply be focusing on playing stripped-down versions of the songs from Painted From Memory, his collaboration last year with veteran master tunesmith Burt Bacharach.

Not unnaturally, as attendees at the show at the Royal Concert Hall in April will doubtless recall, while the two-and-a-half hour event did largely follow this plan, it also showcased one or two of Elvis's older songs from his 22-year, 18-album career.

Since then, though, rather a lot has happened, and consequently Elvis is rather less certain about exactly what he and Mr Nieve will be doing on the very same Glasgow stage in a little over two weeks' time, on December 7. One thing to have happened since the spring is that Elvis's ongoing year-long tour visited America in two separate instalments, one of which included an appearance at the Nude Pyromaniacs' Jamboree, or Woodstock '99 as it was more formally known.

He'd already been to Japan twice, Sweden (with an orchestra), New Zealand, and Australia and he'll soon be heading Rotterdam-wards with that orchestra again before returning to Japan.

Since April, too, Elvis has come to the movie-going world's attention in Austin Powers: The Spy Who Shagged Me, singing Never Fall In Love Again with one of its co-creators, the aforementioned Mr Bacharach. Likewise, Elvis's version of She in another film, Notting Hill, has put him atop the charts around the globe, including sundry south American countries where they'd never heard of him before.

But what's the most important thing to have happened to Elvis since his last Glasgow visit? He had a seven-week mid-summer holiday. He didn't just laze in the sun, though. Nope. Not the Costello way. Instead, during that seven-week holiday he wrote seven new songs which have quickly worked their way into his live repertoire over the past few weeks.

''Folk will get to hear at least some of them if they come to see us live in Glasgow,'' he told me last week by phone from a dressing room in Newcastle's City Hall, ''but not all of them, because seven unknown songs are quite a chunk out of an evening.''

What has inspired this sudden burst of creativity? ''I'm very proud of my songwriting with Burt Bacharach over the past two years, but the intensity of it was so all-encompassing that I developed a real feeling of freedom when it came to writing for myself again,'' Elvis reckons.

One song was co-written with Carole King, however. ''She did the verse and I did the lyrics and the bridge. There are also songs from a story-in-song I'm working on called The Deliveryman.

''Ironically, it's been 10 years since I gave up a similar kind of theatre commission from Nottingham Playhouse because I didn't think I could develop musical themes and advance storylines as anything but a full-time task, and now I come up with this. The characters tell their story in a song, and each character is a woman, each song sung by me as that woman . . . and no, not in a high voice.

''A couple of other new songs just popped out of my head, while others are lyrics for music written by Steve.''

Two other songs are from the movie that Elvis has just completed acting in this year, Prison Song, filmed in and around New York and Philadelphia. ''I have two very small roles in each of which my appearance is very different. The movie is a musical, but not like Oklahoma because it's a serious critique of the American inner-city educational system . . . it's more a hip-hop opera. Q Tip's the star, and Mary J Blige is also in it, plus a lot of r&b and hip-hop kids.''

HE ADDS: ''I play a despairing teacher in a leaky school, facing kids who don't want to be there. One of these kids is Elijah, whose grown-up incarnation is played by Q Tip. I'm also Elijah's public defender

. . . I fail to get him off.''

If you miss seeing Elvis Costello live next month you'll be guilty of missing hearing his new songs for some time to come.

''Being able to write songs at will again means I've no urgency to record them. The world won't stop turning if I don't record in the next three months.''

Elvis's record company is rather keen that he does just that, however, having noted not only the mega-sales success of She, but also the 100,000-plus British figures quickly racked up by Elvis's current Best Of album.

''Me, an artist of 20 years' standing, out-selling Ricky Martin and Whitney Houston,'' Elvis observes with a mixture of pride and wry amusement. ''But I'll only record an LP when I've got 12 songs that I think people will want to hear, and that I like, and that I will want to live with for a few years.

''I will record again within the next six months, maybe towards the middle or back-end of next year, but I've got about another 15 songs I need to finish writing first. It's like having a carpenter's workshop filled with half-made furniture. This has got a leg missing, that one's minus three of them. You can't dash stuff off.

''Then again, you get the musicians together, and book the studio, and record the stuff only to find that the record company won't release the album, because industry wisdom says you can't release an album in summer or before Christmas.

''Plus the thing about recording is that you spend ages getting songs as good as possible and then you go out to do a concert - concerts being wonderful places where there are no rules and anything can happen - and you play your new stuff live for the first time . . . and it's better than anything you could manage in the studio.''

Speaking as a music-lover who's lived contentedly in a Costello-formed world these past two decades, I'll be there to see him live on December 7. You know you must, too.