Note that for the purposes of single line working (bidirectional operation of an otherwise unidirectional signalled line) or a single line (or the reverse direction of a bidirectional line) when the normal signalling is not available (typically due to a failure), the pilot (or the older term pilotman) will be either a Network Rail signaller or a Network Rail MOM.
In most cases, it's a MOM these days.
Note that at any moment in time, for a particular line, or section of a line, there can only be one pilot. Hence only one train should be in section, thus making a head on or rear end collision unlikely.
If the member of staff in the cab is a train company employee, then it's likely to route conducting rather than pilot working for signalling reasons.