Best Roast Beef Sandwich?

[mstatt54]

Looking for an unbeatable roast beef sandwich on a baguette w/ thinly sliced ice berg lettuce. i don't enjoy a sandwich the has mounds of meat on it (e.g. sarges). I also prefer that the roast beef be very thinly sliced. i had the best ever at an italian place near St. Paul's in London. It has not been duplicated. Thank you.