I don't know if it's just me, but I have a heckuva time getting BBC videos to work on demand like they're supposed to ... there currently is, e.g., a video report on that recent pair of sarcophagi found at Newcastle which I can't get beyond the 'loading' stage. I'm curious whether it sheds any light on the state of the child burial ... the caption to the piece reads:

A second sarcophagus has already been opened and removed from the site. It contained the headless remains of a child.

The Press Association's coverage was a bit more clear:

The head of the child appeared to have been removed and placed elsewhere in the coffin, which was an unusual but not unknown practice in Roman times. It is possible the burial included the remains of an older person in the same coffin.

We've dealt with headless burials before in these pages ... here ... here ... here ... etc... they are somewhat mysterious although I personally lean toward 'execution victims' as an explanation rather than 'ritual'. A child (some reports suggest he's about six years old) is a bit of a spanner in the works, though.