Hi Xor

Brilliant works perfectly. My only other query is to check for values in column Q that are >=3 and/or <=4. I have tried both "AND" and "OR" but to no avail:

=SUMPRODUCT(ISNUMBER(Risks!$Q$5:$Q$20)*(AND(Risks! $Q5:$Q20>=3,Risks!$Q5:$Q20<=4)*(Risks!$K5:$K20>=(--("1/4/18")))*(Risks!$K5:$K20<=--("30/4/18"))))

Thanks for your help so far.
Tony