A couple of posts ago I mentioned the show Simon & Garfunkel recorded for the BBC in 1967 ( see: https://roboud56.wordpress.com/2011/01/22/article-in-record-collector-magazine-january-2011/ ). But in 1966 when they were already quite famous they also turnd up in the UK for promotion of their second album ‘Parsley Sage Rosemary & Thyme’ and the hits involved.
Music magazine Melody Maker (July 9, 1966) wrote:
‘S&G Arrive
American singers Simon & Garfunkel aarived in London on Tuesday for TV and club appearances.
Currently at 20 in the Pop 50 with ‘I am a rock’ th famous Paul Simon composition, Simon and Artie Garfunkel appear on BBC TV’s Top Of The Pops (Thursday), ITV’s Raedy, Satedy Go! (Friday) at London’s Marquee Club (Sunday), ITV’s Scene at 6.30 (July 13) amd Light’s Saturday Club.
The appearance at the Marquee Club was on July 10th of 1966.
Here’s the advertisment for this show:
Paul Simon - 'Time it was...it was' 
I’m puzzled by this. I was there and remember the support act being the Settlers, a mainstream folk/pop band who did a lot of telly.
Maybe Al was there too – I can’t recall. But S&G were spectacularly good.