246.54 miles (396.77 kilometres)
from bromley to barnet, which is pretty much north & south of greater london, it's 45 road miles
225 miles taking this route: You will start off either on M1 to The NORTH or on M40 (W), depending on where you are coming from in London. So, if you take M1, you will take M1 to The NORTH to M6 to...
9,771.77 miles (15,726.1 kilometres)
255.75 miles (411.58 kilometres)