Delia's Roast Pork with Roasted Stuffed Apples with Thyme and Parsley

I am making Delia's Roast Pork with Roasted Stuffed Apples with Thyme and Parsley. The recipe is for 2.25kg loin of for eight people. My loin of pork is almost 1.5 kg. How does this affect the cooking times? Thank you