Using the Tfl fare finder, it shows me that the default off peak fare from Norwood Junction to Clapham Junction is £3.60.
But there is a fare of £2.80 via Surrey Quays and Queens Road Peckham if I touch the pink validator at Surrey Quays.
Norwood Junction to Imperial Wharf is £3.60, but there is no cheaper option via Surrey Quays/Queens Road and yet I would be travelling one stop further in the same zone on London Overground. Should there be?