Having seen it tonight, a Redhill guard works the 1916 Gatwick to Reading, does the 2107 Reading to Basingstoke and back and then does the 2234 back to Gatwick.
AIUI the guard for the 2334 to Gatwick does the 2135 from Redhill to Reading.
165130 was the 2037 from Reading, 150002 the incoming train at Reading at 2101 with a 165 taking over with the Redhill guard on the 2107.