Kinnell they int 1/2" thats kin humungous. 1/4" BSPt fer the clutch housing an the timing one fer the 2.5Td is metric. Do a search on here, Trewie asked the same question, but cos he's more intrested in clotted cream an pasties he's fergot.
thanks fellas. confirmed as 1/4" BSP for both the bell housing and the timing belt cover and not a mixture of imperial/metric as discussed elsewhere in other threads.
just a word of advice for anyone else reading in future, my local plumb centre didn't carry the smaller plug size. local discount plumber did, 50p a jobbie.