Is an LPA from a Commonwealth country valid in the UK?

[miranda1]

The elderly father of a good friend of ours has recently been admitted to a nursing home. His son has an LPA that was drawn up in his Dad's home country, India, which is a Commonwealth nation whose laws are based on British laws. He has been told by the NH that the LPA is not valid here, however a friend has told him that it IS valid in the UK as it was executed in a Commonwealth country. What are the rules regarding LPAs drawn up in Commonwealth countries? Are they valid in the UK? What about LPAs from the USA - are they valid here as well? Our friend has a second LPA from USA as his Dad lived there for some years before moving to the UK. Ta.