London weightingˌLondon ˈweighting noun [uncountable] 
money added to the income of someone working in London, because of the higher cost of living there than in the rest of the UK: 
He earns £35,000 with London weighting.
money added to the income of someone working in London, because of the higher cost of living there than in the rest of the UK: He earns £35,000 with London weighting.