have had one or two of these where the seal becomes displaced where the steel pipe enters the top of the slave cylinder on top of the g/box.You may have to remove the air filter and battery/tray for access,if you slide out the horseshoe clip holding the pipe/hose and remove,if there is no seal on the end of the pipe then it may be your problem and will need re fitted to pipe,you can remove the seal from the plastic housing and should fit onto the pipe snugly,then re insert pipe into housing and bleed system,usually just open bleed screw and let gravity bleed it for you,top up m/cyl after.If that is not your problem then if it was an after market slave cyl.fitted then it may be worth while fitting a genuine Ford part. Good luck.
cdc
May 2013