The English surname Grattan, also found in Ireland, is of habitational origin deriving it’s name from any of various places so named. Gratton in Derbyshire is from Old English great ‘great’ + tun ‘enclosure or settlement’. Gratton in High Bray, Devon, is probably ‘great hill’, from Old English great + dun. A number of minor places in Devon are named from the dialect word grattan, gratten ‘stubble-field’. A famous bearer of the name was Henry Grattan the noted Irish politician whose ancestors had come from England in the 17th Century.