Brit Speak - Twigged? - Context

[Steve]

---  Janette <jnferr at ...> wrote:
>
> On 2/20/07, Steve <bboyminn at ...> wrote:
> >
> > Once again I seek out all your knowledgable minds.
> >
> > In a two recent interviews with and about Dan, the word
> > 'Twigged' was used.
> >
> > Care to translate?
> >
> > Steve/bboyminn
> 
> 
> montims:
> 
> twigged = understood  but what was the context?
> 
> 

bboyminn:

Guardian Unlimited -
http://film.guardian.co.uk/interview/interviewpages/0,,2009701,00.html

"He met singer Kele Okereke at the Reading Festival. 
Okereke didn't know who he was, until the actor's friend
said, 'Uh, this is Daniel Radcliffe ...' Then he 'sort of
**twigged** and it was one of those situations where it 
was a bit embarrassing for a moment'."

Guardian - Arts Blog -
http://blogs.guardian.co.uk/theatre/2007/02/post_19.html

"One of the pleasures of the last few days has been 
reading the succession of interviews with young Daniel 
conducted by seasoned hacks who haven't ***twigged*** 
that they've all been given exactly the same interview.
The boy is clearly already a real pro."

I guess the definition 'Understood' does make sense in
both these contexts.

But what is the origin of the phrase? At this point I'm
trying to find a connection between 'twigged' and 
'understood'.

Thanks.

Steve/bboymin