Caplin began his musical career in his early twenties in the New Romantic rock group Animal Magnet, and co-wrote their dance track, "Welcome to the Monkey House" (1981).

[1] He left Animal Magnet to become the “mastermind”[2] behind the 1980s avant-garde new wave pop project Haysi Fantayzee, the other members being Jeremy Healy and Caplin's then girlfriend, Kate Garner.

Their music combined reggae, country, and electro with political and sociological lyrics couched as nursery rhymes.

Caplin Systems pioneered the distribution of real-time financial data via the web, and built some of the earliest online trading platforms for investment banks.

[6] In 2001, he received an Ernst & Young Entrepreneur of the Year award for his work with the company.,[7] and in both 2002 and 2009 Caplin Systems was featured in the Sunday Times Tech Track 100 as one of the fastest-growing technology firms in Britain.