On the X5 - my mistake, I'm sure when I'd previously checked it wasn't that long.
To be fair, what the timetable says and what happens in reality are completely unrelated - the A428 (from the A1 to Caxton Gibbet) starts jamming up from about 0630 and remains that way until about 0900, especially in term time. Same again on the descent from Madingley to the M11.