[Mike Cecil]

Thanks Bruce and Mike .... I gather any set with a serial higher than 86534 is certain to be a Mk3. Just have to find out the lower limit for No.19 Mk3.....

Later edit: Mike, you provided the key, thank you! Looks like, from the list presented of serial numbers on that site, all the ones listed in my original post fall within the range of Mk3 serial numbers, which answers my question admirably.

Thanks

Mike