It is said that on the last supper Jesus and his apostles ate lamb, and from there originates the tradition to eat lamb during easter. Originally lamb was part of seder, traditional Jewish feast that marks the beginning of the Jewish holiday of passover.
Any food made of lamb is loved in many countries, especially at Easter.
Simmering food on low temperature is an old tradition to which electrical slow cooker pots have brought a new dimension.
Lambkin roast beefs are quite chubby pieces of meat, so you should season them beforehand, preferably overnight.