To cook a 2kg raw, unsmoked, boneless gammon ham (UK style), the cooking time depends on whether you boil and roast (traditional method) or roast raw in foil.

Boil and Roast (Most Popular UK Method) Boiling / Simmering Time:
Allow 20 minutes per 500g plus 20 minutes (or roughly 20–25 minutes per 500g), which equals about 1 hour and 40 minutes of simmering in water or stock.

Roasting & Glazing Time:
Method 1 Glazing
Remove the skin, score the fat, add a honey-mustard or maple glaze, and roast in the oven at 180°C Fan / 200°C / Gas 6 for 15 to 20 minutes until golden and sticky.
Total Time: ~2 hours (plus 10–15 minutes resting).

Method 2: Roasting:
Pure Oven Roasting (Wrapped in Foil).
Calculation: Allow 30 minutes per 500g, plus an extra 30 minutes.

For a 2kg joint: (30 mins × 4) + 30 mins = 2 hours and 30 minutes.
Oven Temp: Roast at 180°C Fan / 200°C / Gas 6 (wrapped in foil for most of the time to keep it moist, then unwrapped for the last 20–30 minutes with a glaze).

Target Internal Temperature: Ensure the centre reaches at least 70°C–75°C (or 65°C–70°C before resting).