Pretty dated, like comedians Benny and Harry? (2,3,2,3,5)

I believe the answer is:
as old as the hills
'pretty dated' is the definition.
'as old as the hills' can be an answer for 'dated' (I've seen this in another clue). I am unsure of the 'pretty' bit.
'like comedians benny and harry?' is the wordplay.
I cannot quite see how this works, but
'like' could be 'as' and 'as' is found in the answer.
The remaining letters 'oldasthehills' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
I've seen this clue in The Independent.
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