I'm in Murky's camp on this one.
Completing the 1st grid correctly gives you the starting point for the 2nd grid 1st place name which in turn then yields only 4 possible first letters for the first place name (O, P, R or S). You know there are 30 letters in all to comprise the two place names and they are both 'double-barreled' from the preamble.....so this narrows down the place name options considerably.
Only grumbles were that I made a false start using the 1st grid entries for the 2nd grid but that didn't waste too much time; and I was looking for real words to start with in the 2nd grid but I guess that would have been asking way too much!
Thanks Harribobs, last week's Listener and this defy my expectations of what's possible with simple grids!