From Mental Health Law Online
The donor made LPAs appointing A and B as her attorneys, to act jointly, and C and D to be her replacement attorneys. She then imposed the following restriction: "Both C and D should jointly replace the first attorney who needs replacing so that on the first replacement there will be 3 acting attorneys. No further replacements will be needed." On the application of the Public Guardian the court severed the restriction. There is nothing in section 10(8)(b) of the MCA, which deals with the appointment of replacement attorneys, to displace the fundamental principle that the survivor of joint attorneys cannot act. Where one of the original joint attorneys can no longer act, the replacement(s) will step in and act alone, to the exclusion of the surviving original attorney. This ruling reflects what is stated to be the "better view" in paragraph 4.44 of Cretney and Lush on Lasting and Enduring Powers of Attorney (6th edition). [OPG summary - LPA case.]
Summary from OPG section of Justice website.
Title: Re Druce (an order of the Senior Judge made on 31 May 2011)
Heading: Survivor of original joint appointment cannot act with replacement
Not on Bailii - no transcript