Yogi, disappointed to find that Ewok's 2001 edition of Brewers does not contain the definition of Barnard Castle. But happy that Uncle Professor has the 2005 edition that does.
Meanwhile Ewok found a similar definition in 1984 edition of A Dictionary of Slang attributed (from 1864 no less) thus:
> ‘Come! Come! That’s Barney Castle! an expression often uttered when a person is heard making a bad excuse in a still worse cause’.
Wikipedia may or may not decide that Dominic's visit is worth noting.
Update: observant readers have noted that the rules were very, very clear. Crystal in fact. We even captured a copy of them in a post back in March. I surmise therefore, that members of the cabinet, including the Attorney General, aren't avid readers of c r o s s o a k.