When trad rockers guest on early punk albums

As for played, hrm. Ure was in Thin Lizzy for two seconds, I think. Then there's the whole Buggles join Yes deal, but that's another era.

Guested with 'em live, I think.

Did Lene Lovich sing on Cerrone albums? Damn! I might have to break out that copy of Supernature again.

Aren't guys from Funkadelic on Talking Heads' *Remain in Light? I'm not about to go check, and it's later than punk anyway, plus they're really not "trad" rock in any sensible sense, but still. Also, I guess if we're gonna talk producers, we should mention Eno doing the Heads and *No New York, etc. But that's kind of obvious, I guess.

Not sure it counts, but Led Zep's John Paul Jones produced the second album, Children, by the Mission UK (not that they were really Punk, early or otherwise, but....y'know, GOTHS and all).

Well, you could stretch the point and say that both he and Paul Weller guested on Peter Gabriel's third album...

As for Bowie, he was lurking in Berlin the whole time. Though he was working with Iggy, so there's your punk stuff. :-)

Fripp is definitely on "Fade Away...". I've also got a live Blondie bootleg from around then in which Fripp joins them live on a cover of "Heroes".

As did Lol Coxhill!

As far as being a "punk" is concerned, let us not forget that before upping his credibility by joining The Rich Kids, in 1976 Midge Ure was still a member of manufactured, teeny-bop, glam, Bay City Roller wannabes Slik (remember their hit single "Forever And Ever"?)!

as per Coxhill's Damned live involvement, so it's reported to've really happened, the man has admitted as much himself, and an altogether fascinatin' factoid it verily is... only, glancing topwards, one wishes the thread title could be changed to something like "conspicuous guests with punk bands", for it's virtually impossible to even think, with a straight face, of Lol Coxhill as either "trad" or "rocker"
8-)

For example, www.furious.com/perfect/lenelovich.html says:

In Lene's first true "band", she played the sax, while Les accompanied on guitar. The group recorded a few covers, most notably, Carl Malcolm's "Fattie Bum Bum," but their own singles failed to garner any success. Also, during this time [the mid 70's], Lene was recruited to write English lyrics for the French disco sensation Cerrone. While not being credited on the records, Lene assisted in three of Cerrone's works, including the successful "Supernature." As Lene put it:
"It all started with a vague phone call while I was in the studio with a soul band (The Diversions?). Somebody needed somebody to work with this foreign guy who couldn't speak much English, but he was into disco, and because we were doing soul/funk, they just sort of shouted in our direction. And I, grabbing every opportunity whether I could handle it or not, said I could do that, and because I had put my hand up I ended up being on a plane to Paris and had to figure out how to do this new thing."

Lene Lovich adapted lyrics for French disco star Cerrone include the UK hit "Supernature" - ATLANTIC K11089 and LPs "Cerrone's Paradise" - ATLANTIC K50377 and "Cerrone IV" - S 83282. She also participated in the composing of Cerrone's opera "The Collector" in the mid 80's.

Now, you will probably listen to 'Supernature' with a new consciousness...

"Will there be a happy end
Now that all depends on you... Supernature!"

Not merely live involvement and not subject to any debate - Lol Coxhill played sax on the track You Know on the Damned's second studio album Music For Pleasure - it's one of the few redeeming features of the album.

yesyesyesyes, and more - on Coxhill's Spectral Soprano comp is, a.o. stuff, the outstretched duo number 'Turned Out Nice Again'(8:09), recorded 1998 at Benny's Bar, Bayswater, London (it says in the booklet) - performed by Lu Edmonds: fretless 3-stringed bass banjo + Coxhill: s.sax
Sayeth Lol: "I /.../ have stayed in touch with Lu, playing together now and again at improvised music sessions with him on various instruments."

good for 'em, 's all i say.