The group was organized in 1974 and they became famous by the smooth articulation. Till 1990, Paul Hillier, who had sung bariton part and was a director of the group, produced many excellent performance from 12 century to comtemporary.
His resignation to the group changed the groups' impression. New member Gordon Jones has softer voice than Paul Hillier, so the groups' sound becomes softer and easier to blend. However in directing point of view, new derector John Potter who sing tenor part of the group is interested in Anglican style music more than Hillier and the interpretation of music becomes much concervative, then the attraction of the group seems a little bit lost.
However, performing style for one part with a singer, their quite precise intervals and non-vibrato singing style are very attractive. Therefore thier music introduce us to their own world.
They contribute the bringing to light Medieval or Renaissance masterpices such as Perotin's music or Ockeghem's "Missa Prolationum". On the other hand, they also commites to composition Arvo Perto or other famous composers. These aggressive activities are worth paying attention.
Incidentically, naming of the group is not derived from Paul Hillier but miniature painter Nicholas Hilliard ( in fact "Hilliard" is a nickname of Paul Hillier). This is very famous phrase to introduce the group.