@the_mikey
If you take the ginnel that runs under the tracks, you come out onto a street, slight slope which has a spy shop. Nip in & have a gander at the ways you can keep an eye on people. Left hand side as you head down. Two stone steps outside to help you gain access. Third step will have you inside the shop.
You mean there's more to it than looking through their letter-box, peeking between their curtains and hoking in their bins? If only I'd known.