By Amber Murray The super-prime market in London is booming. More mansions in the capital are being sold, for higher prices, to an increasingly international base. In 2023, sales of super-luxury new-build London apartments rose by 137 per cent to an average of £4,306 per square foot, according to Beauchamp Estates. Supply of luxury houses has also been boosted by an influx of high-end development in prime London areas. While many houses have been either left empty or put on the market as a result of sanctions on Russia, this has not had the effect on the market that analysts warned in 2022, Ch…