London, Dec 13 : India's billionaire "vaccine prince" Adar Poonawalla has reached a deal for London's most expensive home sale of the year, agreeing to pay about 138 mn pound for a 25,000 square foot Mayfair mansion, media reports said. Aberconway House, a vast 1920s home near Hyde Park, will change hands after a sale was agreed by Dominika Kulczyk, daughter of the late businessman Jan Kulczyk, who was Poland's richest man, Financial Times reported. The property will be acquired by Serum Life Sciences, a UK subsidiary of the Poonawalla family's Serum Institute of India, people familiar with the transaction said, it said. The price tag makes Aberconway House the second-most expensive home ever sold in London and the biggest deal of the year, according to luxury property agents, Financial Times reported. The top end of London's property market is insulated from the impact of higher borrowing costs, which have slowed the wider UK housing market this year, because few buyers rely on mortgages. Trophy properties in London have remained attractive to international buyers despite new transparency measures brought in to help target Russian money after the war in Ukraine, and the prospect of tax changes if the Labour party wins the next UK general election. A person close to Serum Life Sciences said the Poonawalla family had "no plans" to move to the UK permanently, but that "the house will serve as a base for the company and family when they are in the UK". The London deal follows multimillion-pound investments in vaccine research and manufacturing facilities near Oxford, the person added, Financial Times reported. /IANS