Two years ago, I asked the British India fellas on twitter why they used Bulgarian counting at the beginning of this song and they replied:
"the guy who owns the car yard next to our studio (Josif) is Bulgarian, and since he was so good to put up with all the noise, we invited him around to do a backing vocal - he couldnt sing - so we just let him count! Thanks for listening"
hope that helps with those as curious as me as to why they had the Bulgarian at the start!
From what I remember from reading an interview with them, they had to rent a new recording studio after theirs got flooded and the new one was next to a used car dealer who befriended them. So they got him to do the countdown. Pretty cool story I think!