With the withdrawal of the Dutch, Don Adrian was employed by the British as a spy master, gathering intelligence during the regular skirmishes along the Kandyan boarder.
In 1815, he had been appointed as Tombi Mudaliyar, in charge of the guides and intelligence agents and trusted aid of John D'Oyly who was the mastermind behind the overthrow Sri Vikrama Rajasinha, the last King of Kandy.
His sons Hector Alfred, Eugene Wilfred (EW), and John Adrian St. Valentine entered the legal profession and the latter two serving as judges of the Supreme Court of Ceylon, while Theodore Godfrey became an engineer and soldier.
Through the latter the Jayewardenes were connected by marriage to the Senanayake family and the Kotelawala, influencing twentieth century politics in Sri Lanka, having formed and dominated the United National Party.
JR who married the heiresses Elina Bandara Rupasinghe entered politics as Ceylon gained independence becoming its first Minister of Finance in the government of D. S. Senanayake.