Writing in 1859 , the clergyman and antiquarian Harry Longueville Jones called it a " small , plain , single @-@ aisled chapel " , and said that one of the small south windows was " a good specimen of its kind . " A 2006 guide to the churches of Anglesey says that the " roofless ruin " of St Mary 's " has the distinction of probably being the most isolated church in Anglesey " .