The London Monogram

This was apparently a symbol for London that was in use during the reign of Alfred the Great. Here are some pictures of coins with it on.

• Silver penny of Alfred the Great, which i saw with my own eyes at the British Library
• Saxon Penny of Alfred the Great, Portrait type, from a Brum museum (upside-down for some reason)
• Alfredlondonrev.1.jpg, Wikipedia, from an example at the Fitzilliam Museum
• Imitation of Alfred's London Monogram type, Southern Danelaw, mid-880s, again from the Fitzwillia Museum
• English Coin, at the University of South Florida, hence the really unhelpful name; again, upside-down

I think it'd make a rather fine symbol for London today.

While i'm at it, does anyone know when, where and with whom the use of 'LDN' to mean London originates? It's in some Dizzee Rascal lyrics, and went mainstream(er) with Lily Allen, and seems to have come from the UK garage community, but details would be good. Must check the OED ...