I think 80 minutes is a better guess than 100....
Gets in a 0810.
Turnround - 40 minutes (based on the timetable) - out at 0850.
80 minutes later - arrives X - 1010.
Turnaround - leaves 1050.
Back into CWL - 12.10
Out at 1245....
100 is pushing it, I reckon....
TA