Ignition always live. ECU problem?

Hey all,

Long time watcher, first time poster.

I have a td5 defender that until this morning was (surprisingly) working fine. Today however I was faced with a nearly flat battery and a live ignition, even though there was no key in.

After much head scratching, wire checking etc I came up with the following...

Ignition is staying on unless I remove fuse 12 ( engine management fuse). As fuse 12 is the direct 12v feed for the ecu I'm assuming there is a fault with the ECU and it's not down to a short anywhere else (how could it be?)

what do we think, am I missing anything that could save me a new ECU?

I forgot to say, when the engine is bump started it starts and runs fine, just won't switch off.

Just reading through other posts. Could oil in the harness side cause the issue, even if there is no visible oil at the ECU end?