Heat oven to 200C/180C fan/gas 6. Put the potatoes in a roasting tin and drizzle with half the oil. Sit the chicken thighs on top, drizzle over the remaining oil and season. Roast in the oven for 30 mins.
Add the cherry tomatoes, olives, oregano leaves and feta, then drizzle with the red wine vinegar. Return to the oven for another 25-30 mins until the chicken is cooked through and golden.