Set the Instant Pot to Sauté, then spray with some low calorie cooking spray. Season the meat well with salt and pepper, then sauté it until it's brown on all sides, then set aside.
Dissolve the stock cube in the boiling water, then add this to the Instant Pot.
Set the Instant Pot to manual for 30 minutes (natural pressure release).
When the pressure is released remove the lid carefully, and add the Worcestershire sauce and stock pot. Stir well to break up the sliced potato. This will thicken the Scouse.
Replace the lid and set the Instant Pot to Manual for 5 minutes (natural pressure release).
Check the lamb is tender and the potato is cooked, then check the seasoning and serve.