Incredibly, while Facebook has a death notice, Wikipedia does not!
In a rush, so...
http://www.heraldscotland.com/opinion/obituaries/13527160.Patricia_Leitch/
(obit)
https://groups.google.com/forum/#!searchin/rec.arts.books.childrens/80th$20patricia/rec.arts.books.childrens/t3Da2JPQIB0/wGMftBJUsxQJ
(birthday post from 2013, with link to booklist and more)
http://www.janebadgerbooks.co.uk/ponybooksfile2/leitchhome.html
(book covers and descriptions)
http://booksandmud.blogspot.com/2015/08/patricia-leitch-1933-2015.html
(remembrance of Leitch, with photos)
http://www.dailyrecord.co.uk/incoming/celebrated-writer-pat-leitch-leaves-6198831#AQtC0w1PZF5gOYoM.97
(another)
Excerpts:
...She grew up alongside her sister Ann, who was three years her junior, enjoying an outdoor lifestyle, running in the fields near the town.
They later moved to Cheshire and Anglesey, where their knowledge of the local countryside coloured Jinny and Shantih's roaming adventures.
Her first tale, For Love Of A Horse, told how her flame-haired heroine rescued the mistreated steed from the circus.
The works have been praised for their realism and accurate portrayal of a young girl's life in Scotland.
The character grew up in the fictional Highland Finmory House, but her gallops through the wild were based on journeys Pat had taken through fields and woodland around Renfrewshire...
http://nzponywriter.com/2015/08/04/patricia-leitch-1933-2015/
(more about her novels)
Lenona.