London Irish head coach Toby Booth said: “Clarke is a natural captain with a wealth of leadership experience at provincial and Super 14 level in New Zealand.

“He is hugely respected within the squad and always leads by example out on the pitch.”

Casey led the Exiles into their first Premiership Grand Final appearance, against Leicester in 2009, and Booth insisted the veteran lock still has a key role to play at the club.

“I would like to thank Bob for his fine captaincy in the past three seasons and stress the important role that players of his experience have on the continued development of our squad,” said Booth.

“The physical nature of Premiership rugby encourages the need for leaders all over the pitch and teams can no longer rely on one leader.

“Clarke will be our figurehead but the contribution of Bob and our other senior players will be paramount to our success on the pitch.”

Dermody, who has eight All Blacks caps, joined London Irish in October 2007 from New Zealand Super 14 franchise Otago Highlanders.

The 30-year-old said: “I have experienced captaincy playing in New Zealand and it is something I enjoy doing. We have a very talented squad again this season and I am confident that we will be able to fulfil our potential.”