Looks like it has the Jaguar part number written on the hose.

Thanks for the reply but I think that is just the hose spec rather than the specific piece. In any event I've now realised that isn't the source. I took the car for a drive and had another look with the engine warm. There was a weep coming from a bleed screw in the hose above. No problem I thought, I'll just nip it up. Unfortunately(and with hindsight rather predictably) the screw was very brittle and so broke off completely and water came gushing out.

Presuming that I just needed to replace the bleed screw I googled it but am struggling to find a part number for that now. It is smaller than the bleed screw on the expansion tank and I'm guessing night not be obtainable separately to the hose. So my next question is - can anyone tell me the part number for either the bleed screw on its own or, alternatively the whole hose assembly? Picture below (the white tape is just covering the bleed screw hole).

Thanks in advance

I can't find any part reference for the bleed screw on its own, the part number for the pipe is LR034624 (Hose And Bracket) - about £80 retail.
Access to the bolt for the bracket looks challenging.

As that looks like a metal pipe it should be possible to find a suitable short bolt with washer to fit the spigot the plastic bleed screw was in. (wistfully remembering when bleed screws were made from brass)

If you put your vehicle details in your forum profile it can make helping with queries easier.

Thanks very much Fifth Horseman. Looks like it is £80 for a bleed screw then - I think I'll just leave the pipe and bracket intact. Good idea about finding a screw - just need to look for the correct size/thread, luckily enough of the old screw remains intact to try and match.

BTW, when the screw snapped off I looked on you tube for ideas on how to get the broken bit out. Saw a video where a guy heated up a flat bladed screwdriver, used that to make a slot in the remainder of the screw, let it cool then just unscrewed it with the same screwdriver. I tried it and it worked like a dream.

Thought my details were in the profile - certainly showing when I look but not sure if I need to do something to make it visible? It is a 2013 5.0 supercharged autobiography. Currently up to 188,000 miles - I try not to think how much I've spent on petrol over the years....

Worth a punt, albeit delivery from China, loads on the site

https://www.ebay.co.uk/itm/185758145586 L405 SV Autobiography LWB SDV8, finished in Aston Martin China Grey by ETO division.

Definitely worth a shot - how they should have been made from the start.

Thanks both. Have ordered one and will let you know how I get on.

In the meantime I've got one of these coming tomorrow https://www.accu.co.uk/hexagon-head-pipe-p...B-M10-1-A2 - as far as I can tell it is the correct diameter and thread pitch and will hopefully get me mobile again whilst the brass one is weaving it's way from the far east.

Success! One £4 bolt (as per the link above) and I'm up and running.

Well the brass bolt from China arrived - and wouldn't fit!

Click image to enlarge