Thanks for your replies.
My sister googled it and one of the suggestions was to catch some wee and sprinkle over it over Jasmine's usual place - I thought that was a good idea and an even better idea was for my sister to put said plan into action
.
Another idea on Google was to get another dog to wee in the garden in the hope that Jasmine would then wee over it. My (other) sister has a Patterdale terrier (Monty) - just the chap! Well Monty came over this evening and kept up his end of the deal, but no joy yet with Jasmine. Maybe this is more of an alpha male type solution.
Nothing has changed in the garden - apart from pulling up a few weeds. OK, quite a lot of weeds. Interestingly (well depending on your interpretation of interesting) she has pooped in the garden since this no weeing malarkey started. I have rearranged some of the garden furniture so maybe that's it.
Off I go into the garden again to try persuade her to wee again - wish me luck!