it sounds like big ends but the engine was like new so i cant see how it would have gone wrong, unless its due to lack of use or contaminated oil? the car has only done 500 miles in 2 years!
Here is a video of it. you can just make it out when i hold the revs still
https://www.youtube.com/watch?v=uOPW87d9TRQ&feature=youtube_gdata_player