Gwendoline Christie worked as Simon Callow's dog sitter.

The 39-year-old actress enrolled at Drama Centre London back in 2000 and while she was there she met legendary British actor-and-writer Callow.

After being employed as his personal dog walker and assistant, the 68-year-old award-winning thespian became Gwendoline's ''mentor''.

Speaking to The Times newspaper, she said: ''The school secretary came to me and said, 'I have a job for you. Simon Callow wants his compact disc collection organised.' He had 4,000 CDs. I met him, fell in love with him, in the non-romantic sense, and he became my mentor. When I left drama school I started looking after his dogs, and I became his research assistant, and collated chronologically every piece of writing he's ever written, for his autobiography.

''In return he told me to be an artist and not to compromise myself. He used to throw books at me and say, 'Take this and read it, and feed your lazy and disorganised mind!' ''

After a few small roles, Gwendoline landed her breakthrough part as Brienne of Tarth in HBO fantasy series 'Game of Thrones', based on the books of George R. R. Martin.

Gwendoline - who plays Captain Phasma in the new 'Star Wars' trilogy - admits her part in the acclaimed show pushed her ''out of her comfort zone'' and made her realise her unique physical features are her strength as an actress.

She said: ''It was a real stripping away and I found it very difficult.

''It was about realising my strength, my height and my androgyny, and really exposing those things in order to feel them. It pushed me out of my comfort zone and expanded my experience of what it is it be human.''

Now Gwendoline will be reprising her role as the Brienne of Tarth in the eighth and final season of 'Game of Thrones' which is slated to hit screens in 2019.