What bird is this please?

Last autumn the family spotted a bird the size and colour of a male blackbird but with red legs, and white speckled plummage on it's back, as if it had been splattered with emulsion.  We have not been able to identify it in any books, and we have tried asking the local rangers.  We spotted this bird again on the 19th of April, unfortunately it is always in the same place, a grass verge on a single track blind bend - not the ideal place to stop and take pictures.   Any thoughts?