It was apparently something that British trip-hop trio Portishead felt very sorry about — the fact that they only backed their recent “Third” album with a single stateside date at Coachella. After all, it had taken Geoff Barrow, Beth Gibbons and Adrian Utley an excruciatingly long 11 years just to complete the project.

But now, by way of apology, they’re actually returning to these shores for a fairly extensive tour this fall, with a date at Berkeley’s gorgeous Greek Theatre on Oct. 21. Some tickets have just gone on sale at the band’s website. The rest are up for grabs July 15.

Why now?

The band has explained that — since they were invited to curate two dates of All Tomorrow’s Parties’ “I’ll Be Your Mirror” festival in Asbury Park, N.J., on Oct. 1 and 2 — they decided to undertake a full jaunt, their first since 1998, starting with two nights at New York’s Hammerstein Ballroom.

They’ll be joined onstage this time by bassist Jim Barr, drummer Clive Deamer and keyboardist John Baggott, with Thought Forms as the opening act on all dates. Apology accepted!