I have finally received a response from Waitrose concerning my delivery of Wild Salmon, which I believed to be farmed salmon.
I have been informed that the salmon I received was Coho Salmon, whilst the usual type of salmon I receive is Sock Eye Salmon. I have no way of knowing for sure whether this is true and that Coho Salmon looks and tastes awful or whether they did in fact make a mistake with their packaging and are unwilling to admit it.
If you buy Salmon direct from a fish monger, I suggest you check the colour before you buy and ensure it is a deep red and not a grey-pink colour and ensure you ask that it is Sock Eye Salmon.