If you have a P60 I think it is from that year it should be fine but really you need to go and speak to the people that issue the things even around BAA airports there are differences between ID units depending on which contractor is running the security.
Its actually a pretty common problem with the amount of companys that have gone in the last few years.
You may also find as well that if it was mainline BMI you were working for your records are actually still about as its been bought by BA.