Cassion Castle Architects' practice philosophy is to employ surprise, ingenuity, realism, humour, and abstraction, to create architecture which is both user-friendly and conceptually rigorous. They believe in user-centered design, and in responding to the site, and their projects are also driven by issues of sustainability.

Cassion Castle began his training as an architect at Cambridge University, before completing a Masters degree at the Royal College Of Art. He worked for various architectural offices including Florian Beigel's ARU before forming Turner Castle in 2000. He subsequently reformed his practice as Cassion Castle Architects in 2006. A recently completed project is the Twofold House: a bespoke home and studio for two industrial designers in East London. This building has been short-listed at the RIBA London Awards 2009 for Best Residential Project and at the Grand Designs Awards 2009 for Best New-Build.