quote...................'but moulds were used till they wore out or the shape was no longer produced. They don't last 60 years)'...............or even apparently that they were melted down during the fourteen/eighteen war as a contribution to munitions, like a lot of garden front railings and other ironwork.
Generally, if the No. is sharp and the glass shows signs of genuine wear, then I always think it's reasonable to assume it was made within a year or two perhaps of the date of Registration - or even earlier. But Pieces are seen where the No. is virtually illegible, or even just a slightly rough area where is should be, and then the age is going to be vastly more recent.
I'm really not sure where the '25/30 years' comes from - Board of Trade Registrations lasted for a period of 5 years, and as happened quite often with a successful design, it could be extended for further periods, but I've not looked at this particular Registration in the archives, so don't know it's history or the details of its extensions, if any.
If you care to shove a reminder in the 'Look Up' section regarding Registrations, I'll try and remember to have a look at this one next time I visit Kew.
I know very little about Davidson's pressed glass, but do see pieces with these blackberry prunts quite commonly which does back up the comments that 533040 was one of the longer lasting designs.
This would be quite a useful piece I'd imagine.
