Obtaining Lasting Power of Attorney

In order to be allowed to deal with someone's financial affairs you need to have Power of Attorney. Without this, as mentioned in the NatWest post, the banks will act entirely in their own interests.

If the person that you are taking Power of Attorney for still has sufficient mental capacity to make their own decisions they can download application forms from http://www.publicguardian.gov.uk/forms/Making-an-LPA.htm. A doctor or other professional will need to sign this form to confirm that there is sufficient capacity.

A Lasting Power of Attorney is by far the best way to manage someone's financial affairs. Just because your elderly relative has Alzheimer's or dementia does not mean that they are not mentally competant to make decisions.  The guiding principles of the Mental Capacity Act are here http://www.publicguardian.gov.uk/mca/mca.htm

An older form of Power of Attorney called Enduring Power of Attorney is also still valid if it was made before 1st October 2007. There's information about this here http://www.publicguardian.gov.uk/arrangements/epa.htm.
If Attorneys are appointed jointly under Enduring Power of Attorney and one of them dies then the whole Enduring Power of Attorney is invalidated.

If the person no longer has sufficient mental capacity the only way to be appointed an attorney is to apply to the Court of Protection to be appointed a Deputy which is a slow and costly business.
http://www.publicguardian.gov.uk/about/court-of-protection.htm

When a Lasting Power of Attorney is applied for and multiple Attorneys are appointed a choice must be made as to whether these Attorneys should act independently or jointly. If you are appointed independently you and the other attorney can act alone so this is appropriate if you agree with the other attorney about all courses of action. If you are appointed jointly then you will both need to sign all the forms that banks require, all cheques and so on.  If one of the jointly appointed Attorneys dies there is provision in the Lasting Power of Attorney document to appoint a replacement.