B v B  EWHC 543 (Fam)
"This is an application by the Official Solicitor for an order that Mr B do pay the Official Solicitor’s costs, on an indemnity basis, of acting on behalf of Mr B as his guardian ad litem, until the Official Solicitor was discharged by order of 19th August 2009." [Summary required.]
Possible Bailii link (not there when last checked, but it might have appeared since 0700 this morning!)
In 'COP costs cases' category as it is the nearest relevant category.