Funding source associated with London sewers? (3,3,4,2,12,6)

I believe the answer is:

the old lady of threadneedle street

I believe this clue is a double definition.

'funding source' is the first definition.
(nickname for the Bank of England)

'associated with london sewers?' is the second definition.
(sewers as in people who sew)

I've seen this clue in The Independent.

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