I was a little bit annoyed that he killed it at first, but after sending in the photos to Rentokil and getting their response (see below), I have changed my mind....! Further, it has now occured to me that this is in fact what might have killed my dog - I never thought to check him for a snake bit.
From Rentokil:
'Good Morning Florence
It looks like a West African Green Mamba (also called Western Green Mamba) which is highly venomous, it is more than capable of killing a human if not treated quickly. I sent it to a colleague in South Africa who is more expert than us. Whilst he said whilst not conclusive, he agrees with our ID. I’ve attached a library photo of one below and a description for you to compare. I think you did the right thing killing it!! It’s likely to have been brought here as a pet as it’s not normally native, they normally stay in trees.'
