In the case of PLK & Ors (Court of Protection : Costs)  EWHC B28 (Costs) is essential reading for anyone claiming more than Guideline hourly rates, where a summary can be found at https://www.civillitigationbrief.com/2020/10/01/guidline-hourly-rates-considered-in-court-of-protection-inflation-can-be-taken-into-account-on-assessment/.
Essentially, at paragraph 35 Master Whalan states:
“I am satisfied that in 2020 the GHR cannot be applied reasonably or equitably without some form of monetary uplift that recognises the erosive effect of inflation and, no doubt, other commercial pressures since the last formal review in 2010. I am conscious equally of the fact that I have no power to review or amend the GHR. Accordingly my finding and, in turn, my direction to Costs Officers conducting COP assessments is that they should exercise some broad, pragmatic flexibility when applying the 2010 GHR to the hourly rates claimed. If the hourly rates claimed fall within approximately 120% of the 2010 GHR, then they should be regarded as being prima facie reasonable. Rates claimed above this level will be correspondingly unreasonable.”
It is important to note that the observation and direction is intended to be in relation to claims that would likely be limited to guideline hourly rates only and not to limit claims which would justify an enhancement as a consequence of the relevant factors of the claim.