Wipe the chicken joints, spread a little of the butter on each joint, arrange in a roasting tin and cover with a buttered paper. Place in the centre of a moderate oven (180 °C., 350 °F., Gas Mark 4) and bake for 1 hour or until tender. Remove from the oven and allow the joints to cool.
Meanwhile, peel the cucumber and cut in half lengthways. Remove the centre seeds and then dice the flesh. Place in a saucepan, cover with cold water and bring up to the boil. Draw off the heat, drain and allow to cool. This blanching removes indigestible juices and improves the colour of the cucumber. Combine the chicken and cucumber in a basin, season well with salt and pepper and toss to mix.
For the dressing, blend the cream, mayonnaise, strained lemon juice and mustard. Check taste, adding more mustard if liked – for the best flavour use English mustard. Pour the dressing over the chicken and cucumber and toss well. Pile the salad on to a serving platter, garnish with slices of hard-boiled egg and sprinkle with finely chopped chives. Serve with brown bread and butter.