I wish to create a range of CheckBox's (A5:A30) that if checked a
formula in AA1 will count the number of "Ticks" in a non-contiguous
range, say in A7;A9;A15 etc

Is this possible?

Think I worked this, you have to exit the design mode before actually
you can 'tick' the box!! I thought you had to enter TRUE or FALSE in a
linked cell

Think then this formula (ex Ron Rosenfield) will count the TRUE
checkboxes =--OR(NOT(ISERR(SEARCH("TRUE",CONCATENATE(N14,N16)))) )