The book is fairly old and I too am allergic to the word "Celtic". I disagree about high crosses only being associated with monasteries. At least one of the Eleanor Crosses is referred to as a high cross - Tottenham High Cross. Like other terms on this thread, quite specific terms soon come to be used in a more general imprecise way. I do still support the concept of high crosses being those raised on high -(ie free standing) and being the distinguishing factor from those carved on stone slabs -ie not fee standing.