Complex sentence: The Wick--was a "favoured gathering place" for these get-togethers, at which the participants included ex-Beatle George Harrison, Wood's Faces bandmates, and members of the Rolling Stones.
Split into simpler sentences: The Wick--was a "favoured gathering place". Among the participants in these get-togethers were ex-Beatle George Harrison, Wood's Faces bandmates, and members of the Rolling Stones.