Looks like a nice one! The GMT hand on the earlier ones wouldn't be the chequered type (I think someone mentioned it looked faded), so all looks fine and a nice example. These were the beaters of their day and it's very, very hard to find a pristine one but this looks to be very nice and all correct.
There's a bit of dial variation on some of these and the addition of the word automatic doesn't really add any additional value. You can't adjust the GMT hand manually unfortunately and I don't remember any of the Guides I've owned having a quick set date feature.
Price wise though, around £1,250-£1,500 depending on service history etc would be fair I'd say