Big hair with the pre-Raphaelites, 17 Orkney stand-outs and night frights in Derry – the week in art

William Morris and the gang collaborate in Cambridge, artists celebrate at Stromness harbour and Halloween haunts Derry – all in your weekly dispatchA Call to Art If you feel you need to see another exhibition about William Morris and the pre-Raphaelites, get yourself to Cambridge for this exploration of late Victorian art and politics. • Fitzwilliam Museum, Cambridge, until 3…