I have tried google searches and on-line manuals but can't work out how to tell if a receiver or processor can handle uncompressed 5.1 PCM and what is needed besides an HDMI connection. Any insights please?

Uncompressed 5.1 PCM can be carried over an HDMI v1.1 connection, but it is not always east to tell if an HDMI-equipped receiver (particularly an older one) is at least v1.1.

Thanks Gonk! Your answer plus yet another google search suggests that a processor or receiver that receives audio over HDMI 1.1 or higher can handle uncompressed 5.1/7.1 PCM - is that correct?

That is correct. (And for what it's worth, the HDMI FAQ in my sig has a fair bit of detail about the different versions of HDMI.)