The first suggested index made little to no difference (probably why you edited the post!) and so I removed from my DB after testing.

The second suggested index halved the running time. This is without the other previously suggested indexes in play. I don't know if this was intentional or not but the second one is also the same as you suggested earlier implying that your first instincts were correct.

With this second query in place my 'problem' query example is now running in under 30 seconds compared to the original posted 50+ seconds. Even better, the 'full' query is now running in under 60 seconds when previously it was taking nearly 2. Quite a result thanks to you.

I really appreciate you taking the time to help me in this matter. In deciding on the most efficient index to build did you look at the fields used in the query and include those in a query, or was there some other clue to help you have that suggestion?