Andrew Johnston could not arrive any more prepared. Flanked by two members of staff, the London-based managing partner of Addleshaw Goddard is fresh from a bracing morning dip in the Forty Foot, and starting to feel his toes again, when he sits down to talk with The Currency on the sidelines of the international firm’s four-day teams conference at the Clayton Hotel, Burlington Road.  Four years on from the firm’s arrival in Dublin via a merger with Eugene F Collins, the Irish hub is hosting a gathering of around 1,500 of the firm’s lawyers based in the UK, Ireland, Europe,…