While still thinking about DAB for the LS, I noticed on friday on way home from work that FM reception was worse than it had ever been.
So saturday I got the boot open and investigated the ariel
On removing the co-ax plug at bottom of ariel mounting, it looked a bit 'greasy'.
So got out my cotton buds, some isopropyl alchohol and gave it a good clean.
Actually quite shocked at the amount of rusty coloured gunk that came out.
Cleaned both the end stump of the ariel mount, and the female socket, dried the off and then sprayed with electrical contact cleaner.
The end result, on the drive into work morning the FM signal was fine (I travel across a boundary between the Oxford and Wenvoe transmitter handover), which tells me the gunk was the problem.
I would guess the boot gets to much climatic change that condensation is a problem, and with the LS400 leaky boot syndrome the ariel absorbed more than usual moisture.
A 10 minute job well worth doing if your FM reception is naff.
Also noticed improved MW and LW reception (not that these are used)