Greengage woes

That's what happens to the one in my Daughters garden, will be interested in the answers

Some of the more knowledgeable and experienced gardeners helped to ID the fruit, but could only offer advice that it is missing some nutrients - unable to help further. Hopefully the community here will be able to offer some sound advice

This may not be of any help, but I've noticed an unusually large amount of surface russeting/ corky marking and scabbing on the plums I grow (eg Czars, Warwickshire Drooper and Victoria), plus much more oozing from the ends of the fruitlets than usual, even though the crops are very heavy. This has occurred at a very early stage in the development of the fruitlets. Some of the worst-affected fruit is bound to rot, but I don't think that a moderate amount of marking is too much of a problem in itself, as they are, primarily, surface blemishes.

I looked in books and around the internet for possible pest and disease causes and couldn't find anything convincing. However, under abiotic (i.e. environmental causes), I eventually came across a number of possibilities. You could check these out. They are 'Russet scab', 'Wind scab' and 'Lacy scab' -apparently caused by excessive wind and/or rain during or soon after flowering. These conditions can make the plums unmarketable commercially, but the majority should still be fine to eat and use domestically.

Of course I could be very wrong, but the plum in your photo looks to be suffering in this way. I would guess that some very badly marked fruits are bound not to develop to maturity, as the associated or underlying stress will have knocked the developmental physiology off its normal course.

Interesting, my Greengage hasn't fruited this year either.