Rule 159 of the Highway Code tells drivers that
Before moving off you should
- use all mirrors to check the road is clear
- look round to check the blind spots (the areas you are unable to see in the mirrors)
- signal if necessary before moving out
- look round for a final check.
Move off only when it is safe to do so.
Like Eric Morecambe, many drivers in London do all the right things, but not necessarily in the right order.