Australian infrastructure fund AMP Capital has bought almost half of Luton Airport, the UK's fifth-largest, marking a vote of confidence in the post-Brexit performance of London's economy.

AMP has acquired the stake from French infrastructure fund manger Ardian. Financial terms of the deal were not disclosed, but AMP is likely to have paid around £350m for the stake, according to a person close to the company, valuing it at just under 15 times earnings.