Grate the zest of the lemon into a bowl. Add the butter and a generous grinding of fresh black pepper. Mix everything together well.
Gently lift the skin from the chicken breast and smooth the butter over the chicken under the skin. Press the butter all round the chicken and spread any leftover butter over the chicken.
Halve the lemon and place both halves in the cavity of the chicken.
Roast at 190C for 1 hour and 15 minutes, or until cooked through. Remove the chicken to rest and keep warm.
Add the roasting tray to a hob on medium heat and add the Atkins & Potts British Chicken Gravy. Cook until just simmering and serve with the roast chicken.