Boris Johnson has compared the Irish border to that between Camden and Westminster

Boris Johnson has dismissed concerns that leaving the EU customs union after Brexit could lead to a hard Irish border by suggesting that crossings of the frontier could be monitored by technology like travel between London boroughs.

The UK's Foreign Secretary said "there's no border between Camden and Westminster" as he suggested that goods crossing between the Republic of Ireland and Northern Ireland could be subject to electronic checks, in an apparent reference to the congestion charge.