Probably a bit off-topic but I seem to recall from schooldays learning that many moons ago, possibly in Anglo Saxon times, "Ham" meant village (or it might have been hamlet). "Ton" meant town. So in West London (where I grew up) we had Teddington, Petersham, Ham, Kingston, Hampton (just to confuse things!). There are loads of examples throughout the country, sometimes with "Ham" as a separate word, sometimes not. Towns were bigger than villages and traditionally I believe they tended to have markets, whereas villages didn't. "Bridge" and "Ford" spring to mind as other placenames that were descriptive.
Although London postcodes might have been introduced in the 1800s, I think this may just have been the general areas such as WC, EC, W, NW, N, NE, E, SE, SW - if you look at old postcards and printed material from the early 1900s they tend to say things like "London W" rather than "London W1". I'm not sure when the London districts were given numbers but my Mum used to know them all - she was a London telephonist in the 1950s. I used to know the W ones too and can remember being told they ran alphabetically once outside the very central part. W3 Acton, W4 Chiswick, W5 Ealing, W6 Hammersmith, W7 Hanwell, W8 Kensington, W9 Maida Vale, W10 North Kensington, W11 Notting Hill, W12 Shepherds Bush, W13 West Ealing, W14 West Kensington. There's probably something on Wikipedia.
Postcodes as we know them today (W1 1AA, SW1A 0AA, B5 4BU etc) were introduced roughly around the same time as decimalisation or our EEC entry I think - again, probably wikipedia will say. I remember we had a sticker on the side of a kitchen cupboard and UB3 4QX is a postcode I've never forgotten (the area looks very different now!)