Made contact, nothing resolved yet but at least I know things are moving now. They are trying to get me re-instated on my original flight first but will then look at re-routing if this is not possible. Should hear something late today or early tomorrow.

Thank you all for the advice.

Best of luck. ^

Not heard anything yet, will have to chase them again in the morning.

Great news!

Spoke to BMI again and we're now re-routed coming back on a United codeshare via IAD. Still in economy but just happy to have confirmed flights.
The good thing is they were also able to reserve seats (4 together) for both legs which I couldn't get done before on our outward leg via the ICC.

Thank you for all the advice.

Was any explanation offered as to how a flight sector booked and confirmed on the bmi website got cancelled ?

It's something to do with Virgin, BMI confirm the booking then send it through to Virgin and they then cancel it a few days later. They did say that they have quite a few other people in a similar position at the moment. Because we fly out in just over a week they re-routed us today as it was unlikely to get resolved with VS before we go.