Spoke to Mr M, bought memory on their assurances, recevieved it, fitted it (having read some on-line instructions), it worked. Sorted.
Review by confirmed purchaser
Took me a while to work out what spec my computer was (memory slots, banks, dual channel etc). It was difficult to get a clear answer from the internet, but I spoke to Mr Memory and they assured me what their website recommended for the computer would work. They were right... very useful upgrade!