What would these wire's be for? It is a picture of my passenger foot well. I know I have been putting up a couple different things lately but lets add this one to the list, why not. 

Only way to really tell is to either trace where the wire goes or check what pins on the ECU they're connected to .

Otherwise it's a bit of a guessing game of what aftermarket gauge,sensor ,alarm ect attaches to the ECU. 

Is it the two thick black leads? Can you post a bigger picture please?

Hopefully these are better pictures.

car stereo aerial cable?

Yes it is the aerial cable for the car stereo

Thank you, I have now learnt my ecu has been damaged and will need replacing.  I have been sent quotes for a brand new one (way too expensive) and a second hand one almost half the price but still with reprogramming and install it's more than I am looking to spend. What would my options be? Could I just buy one from a wreckers myself and plug and play or will it need programming anyway? I have one key and no immobiliser. I need to get my car back running asap as it's my daily. Any advice would be appreciated.

I would go for the breakers option to try and save the money - you may have an issue with immobiliser - not yours but the car it comes from. This means you may end up changing the clocks, barrel, ecu and immobiliser box

if it is water damaged,re-locate the new or secondhand so water cannot distroy it again

On 1/30/2021 at 6:02 PM, nictriumph said:

if it is water damaged,re-locate the new or secondhand so water cannot distroy it again

I would want to know how the water got to it in the first place? Where it is located it shouldn't sit in water unless water is at least 3cm deep in the foot well of the car 

I had a mobile mechanic come to me to fit one he sourced from a wrecker and it was reprogrammed and the car is now back to normal. I was parked outside of work and the street flooded, nobody knew until we went on break. The water was high enough flood my passenger side as the street is on a lean and some water got into the drivers side but nothing compared to the passenger side. 

That is great to hear - result!