Im looking for a new king size pocket sprung mattress

I'm looking for a new pocket sprung mattress for a super king size bed. Our current mattress is a Hypnos pocket sprung with a top layer of memory foam and is over 10 years old.
My weight is 17stone and my wife 13 stone and 5'9" in height. Our general preference is a medium mattress and as we both sleep on our sides it needs to be giving. Your recommendation would be greatly appreciated.