Diesel leak

I appear to have a diesel leak that I can't seem to stem. It appears to be coming out the bottom of the CAV injector pump. I don't know what the part is, or what it does.

I guess what I'm asking is: Has anybody had this leak before, and what was done to stem it?

it's on a 19J, fitted in a 1986 LR 110 CSW

I think that is a sort of pressure regulator and looks like rot has set in.
Contact Diesel Bob, find on line, nothing they do not know about diesel stuff.

Not sure if this is the correct one? but gives you an idea what to look/ask for, looks easy enough to change.

https://www.ebay.co.uk/itm/32378551...MImZze5tD28AIV_QIGAB186gipEAYYASABEgJpgvD_BwE

Diesel injection pumps at the bottom of lynal's link also good to deal with, give them a ring.