A lad at my work is having issues on his 2008 plate Mondeo, so thought this would be the best place to ask.

He has 2 keys and one needed a new blade fitting so he got Thompsons to fit a new blade to the fob bit of the key and all seems well until he tries to start it, the key will lock and unlock the car and also will let him turn the electrics on but it won't fire the engine up, any ideas.

 

Sounds as if the immobiliser chip (which is needed to start the car) either isn't coded to the car's ecu  or is missing/broken or not compatible. The fob itself works the remote door  unlocking but the immobiliser chip, which  is a seperate element in the key, has to 'talk' to the ecu. There should be a flashing red immobiliser  light on the dash that will go out when the key is inserted. I take it that the other key works fine? 

I will ask about the second key but assume it works.

He's holiday for a few days but will check about the red light on the dash. 

He did say he's not used the key for a few months before he got the blade changed, if this makes any difference. 

Can he get a new fob part of the key or the internals and recode it to the car?

The fob part is nothing to do with the immobiliser part, and has a seperate function to the immobiliser part. The immobiliser chip is like a little glass torpedo and  is embedded into the fob (if it's a push button fob) or into the end of the key if it's not a push  button fob. 

Here, have a read of this wiki entry on the subject :

https://www.fordwiki.co.uk/index.php/Keyfob_Programming