Well I was expecting today to spray the hose and it all be fine. Nope. Seems there's also a small hole in the bodywork under a rubber strip which is letting water in. More silicone and see what happens later.
Is it a hole that's supposed to be there or a rust hole ? It could be a drain hole which if it's letting water in means it's blocked somewhere, siliconing it will make it worse (well it won't make it betterrer).
Get a long piece of wire and have a poke around in it, see if you can blast some water into it under pressure and if you can find where the exit of the drain hole is and do the wire poke in there. The exit is where the blockage is most likely.
Found this which seems to cover most leaks on a Mondeo ;
http://www.mirez.co.uk/WaterProbs.htm