OK..Problem solved thanks to you guys! Turns out that TriMark have a distributor here in the UK. They carry those latches as a stock item! Much cheaper than Gibbon as well. I am really pleased and would not have found them without your help.
Henry...Do you have a link rod attached to the latch which is then connected to an internal door handle?
I am going to modify 3w outside locking handles to fit my 5w as locking handles are not available for a 5w. Plan on using an original looking internal handle.
I really appreciate this guidance....Thanks again!