the two little stone heads from Hexham — anyone know where they actually ended up??

Right so this is the one that genuinely creeps me out and I can't find a clean answer anywhere. 1971, two boys, Colin and Leslie Robson, digging in their garden in Hexham, Northumberland, pull up two small carved stone heads, about an inch and a half. One 'boy' skull-like, one 'girl' with hair carve……