Thanks for your question. I'm afraid I don't know the answer but I'll make sure we find out for you and let you know.
Cooking this stew in the slow cooker is a great idea – the longer you cook it, the tenderer the meat will be! To adapt the recipe for a slow cooker just follow steps 1-3 as usual and then cook on low in your slow cooker for 6 to 8 hours.
Let us know how you get on!