latest discovery of cremated human neatly into a cooking pot and set off at the side of the historic river walbrook , in london , has experts questioning whether they were part of a gruesome ceremony .
when about 20 skulls were found buried in clusters in the sediment of the historic tributary in 2013 it had been thought that they had got there down stream after being eroded out of a roman cemetery to the north - but new evidence suggests otherwise .
scientific tests are continuing on the cremated remains , with the possibility the grim ritual theory may be confirmed and that most of the seven skulls found so far are heads of executed criminals .