You were planting a bed of begonias round by the south side of the house yesterday afternoon, were you not, Manning?
Manning is not believed to have been planting a bed of begonias by the south side of the house yesterday afternoon, given his orders to clean the north side instead. 
mnli hypothesis: Manning is not believed to have been planting a bed of begonias by the south side of the house yesterday afternoon, given his orders to clean the north side instead.  premise: You were planting a bed of begonias round by the south side of the house yesterday afternoon, were you not, Manning?