Do you have the tag number - or are you able to find it out - where did you find out that it was on a BA RUSH tag ?
At least they are getting it to you - had you left your phone onboard a flight into EDI - its passed to the outsourced EDI lost and found service - min £20 PER ITEM (if you pick it up) and it wont get catalogued for 2 business days at least ....