Well it's not technically a tracker mortgage - but Coventry have always had lifetime rates which, in the past, tracked a Coventry Bank Base Rate - which mirrored the Bank of England base rate since it's introduction (I believe about 10 years or so).
The wording has changed to now show 'variable for term'. In reality, it's HIGHLY unlikely that Coventry will change this beyond mirroring the Bank of England base rate going forward. This is the general advice of a lot of mortgage brokers in the UK. In the highly unlikely event that Coventry pump rates up well in excess of BOE base rate, the product is flexible so you can move away (albeit, losing your fee).