What does the name "Tiggy" mean?

Posted by Starkgaryen12@reddit | AskUK | View on Reddit | 224 comments

Tiggy must be a fairly common name (or maybe pet name) in the UK, right? After all there is an actress called Sienna Tiggy Guillory, and the nanny of the princes William and Harry was called Tiggy (even if her real name was Alexandra).
I would like to know where does it come from, if it's a stand-alone name, a pet name, both or neither.
Thanks in advance. Cheers