So you bought a  Cooke & Lewis's Fabienne toielt from B&Q a few years ago and are now searching for a replacement seat?  Well search no further:

https://www.replacementtoiletseats.co.uk/ourshop/prod_7106618-RTS-V20-Square-Slow-Close-Toilet-Seat-Quick-Release-84340.html

Suitable for the following makes as well (all subject to measurement, please check your pan and check hinge width)

B&Q Fabienne Cooke & Lewis toilet pan

BathStore Apex back to wall pan 

Bathstore Lucille Short Projection

Vitra S20

Rak Series 600

Kartell Options 600