Finally tasted the mystery pear today. I'm inclined to think it must be a sport of Dr Jules as it has a similar flavour. Sweet, juicy, somewhat coarse and granular but with a distinct flavour of pear drops. Possibly a more buttery quality than the original. Skin - slightly rough like other russeted pears, but reasonably thin with no trace of bitterness though a pleasant acidity. Difficult to make a direct comparison, as I picked my sole Dr Jules a little too early, and this a little too late. Ripened a good 6 weeks later than the parent.
Not sure how marketable it would be as a new variety, this part of the season is not short of nice cultivars, but I will graft it on and make enquiries.