sussex police 011 44 1273 475 432
surrey police 011 44 1483 571 212
Nutley doesn't have its own force--it's covered by Uckfield. Without a full address or post code don't know which station covers the area--thinks it's the sussex one.
DON'T use the 8458 number as it'll cost a fortune from the states.
May need to contact american embassy in the UK but police will know.
British airways also allows a 16 y.o. to act as temporary guardian for a younger sibling when flying if mother doesn't have her own passport. Good luck