The extent to which an asset contributes to the architectural or historic interest of any group of assets of which it forms part, particularly where assets comprise an important architectural or historic unity or a fine example of planning, where they make a significant contribution to the streetscape or area or where there is a historic functional relationship between the assets.  Sometimes group value will be achieved through a co-location of diverse assets of different types and dates; groups of assets that together fulfil one of the other criteria.