The Butler

The role of the Butler is played by Angelo Muscat, he was the only really permanent character in the series aside that of Number 6, although he did not appear in all the episodes.
The Butler appears to be in service of
the authority,
mostly the current Number
2 or even the omni-present Number 1. In Fall
Out he changes sides as Number 6
finds himself in charge.
The Butler never speaks a word of dialogue throughout the series.
Angelo was born in Malta, he moved to the U.K. following the death of his parents. He appeared in Doctor Who and also in various theatre roles.
The original script for Arrival describes the Butler as a tall man, but McGoohan was so impressed with Angelo that he altered the script to include him instead.
Sadly, he died in October 1977.