Farringdon

Farringdon is a district in central London, in the modern borough of Islington (London, England).

In London Labour and the London Poor:

Of the Quantity of Shrubs, "Roots," Flowers, etc., sold in the Streets, and of the Buyers. (Volume 1)

Of Two Orphan Flower Girls. (Volume 1)

Watercress Girl. (Volume 1)

Euston Square

Euston Square is a square in the modern borough of Camden in central London, England.

In London Labour and the London Poor:

Of the Uneducated State of Costermongers. (Volume 1)

Eaton Mews

Possibly refers to Eaton Mews in Belgravia, London, which would have originally been stables for houses in Eaton Square.

In London Labour and the London Poor: 

The Whistling Man. (Volume 3) [as Eton Mews]

Eton

Eton College, founded 1440, is a prestigious public school located in Eton, Berkshire, England.

In London Labour and the London Poor:

MEETING OF TICKET-OF-LEAVE MEN (Volume 3)