Quick reminder from the Senior Courts Costs Office Guide 2013 as to the status of a signature to a bill of costs, which is still much misunderstood by many law costs draftsmen and costs lawyers:
“The signature of a statement of costs or a bill for detailed assessment by a solicitor is in normal circumstances sufficient to enable the court to be satisfied that the indemnity principle has not been breached in respect of costs payable under a conventional bill: Bailey v IBC Vehicles Ltd  3 All ER 570 CA. However, the same may not be true in respect of costs payable under a conditional fee agreement: Hollins v Russell  1 WLR 2487.”
Note the comments concerning the signature not necessarily being sufficient where there is a CFA. No mention of this being limited to pre-November 2005 CFAs.