Roast chicken masala and potatoes

Name: Roast chicken masala and potatoes
Ingredients: 4 tbsp lemon juice; 2 tbsp peeled, finely chopped root ginger; 2 tbsp finely chopped or crushed garlic; 3 hot green chillies, finely chopped; ½ tsp salt; 1 tsp ground coriander; 1 tsp garam masala; 1.75kg (3lb 14oz) whole chicken, skin removed; ½ tsp chilli powder; ½ tsp freshly ground black pepper; 2 tbsp olive or sunflower oil; 5 medium potatoes, peeled, halved lengthways, and cut into 5x4cm/2x1½in chunks; ½ tsp of salt; ¾ tsp freshly ground black pepper; 1 tsp ground cumin; ½ tsp turmeric; 1 tsp Kashmiri (mild) chilli powder