How to repair very old land drain?

[mpeill]

I have had the need to enploy a digger with operator to excavate a deep hole in my garden. In the process, we found a very old land drain (I think, but definately not foul) which crossed the hole, and is now severed with a 3 meter gap between one end and the other.
The pipe is clay/pot, but very irregular in shape roughly round but partly flat, dating from the late 1800s.
Once we've pumped the water from the large hole, what can be used to bridge the drain ends, being none-cylindrical and certainly not to any standard size, but approximately 6" OD across.

[welsh brickie]

you can buy flexible field drain pipe from most builders merchants cut it to length and lay it in the gap and cover it with 10mm gravel