The London Borough of Havering. Used to be Essex until London was expanded in the 60's.
Contains the towns Romford, Rainham, Hornchurch and Upminster.
Still has the Essex 'RM' postcode and the towns within Havering are still classed as Essex by most people although it is served by London transport and London Met Police and is classed as Greater London.
Most famous for containing the chav town of Romford
Neighbours with the London Borough of Barking and Dagenham (West) and London Borough of Bexley (South). Essex surrounds it to the east.
Right at the end of the London Underground District line at Upminster, Upminster Bridge, Hornchurch and Elm Park, stations which most people don't use because it takes years to get into the city centre that way.
Nothing really special here, its just confusing as to where it officially is located due to it being both Essex and London :P.
London Borough of Havering, the first London Borough to the East but properly known to people as being in the county of Essex.