M@ Londonâs Most Inconvenient Plaque Marks A Forgotten Roman Site For many of us, a trip to the very northern extreme of the Jubilee line would be adventure enough. How often do you take a ride out to Stanmore for the fun of it? But add to that a walk of over a mile up one of north Londonâs tallest hills, and then a scramble through a patch of overgrown brambles and you might find this: Itâs what I like to think of as Londonâs most inconvenient plaque, and probably one of the least visited. It marks the lost Roman pottery (and possibly settlement) of Sulloniacis. Actually, it's not even a proper plaque - more a disc of paint on wooden board, styled to look like an English Heritage Blue Plaque. Humble and remote the memorial may be, but it does mark one of Roman London's most important outposts.