I am 5′ 4″ and I ride a 13″ Jamis Diablo with front suspension (Rock Shox Indy XC). The bike is the right size for me and I know that Jamis also does an 11″ version. This is, I think, mostly sold as a trials bike. I am not sure how easy it would be to find a Jamis supplier in the UK as it is an American make and I have never seen an ad for it in Mountain Biking UK or in Mountain Bike World. Kona and Voodoo also do a small size bike, and they are both available in the UK.
Their frames seem to be measured slightly differently to normal and their 16″ frame is actually like anybody else’s 14″. Therefore, a 14″ Kona is probably like a 12″. The Kona and Voodoo bikes have a very steeply sloping top tube, which makes them seem even smaller. If you want to go really upmarket and spend a bit more, the Fat Chance Yo Betty is made specifically for smaller riders, with geometry designed for a small bike, instead of being just a cut down version of a bigger bike.
Good luck, I hope you can find something that fits and will let you get your suspension fork. I am 5 foot tall and have just bought a 14 inch Kona Lava Dome. Its great to have a bike that actually fits me after riding a too large frame for years. The Lave Dome seems pretty light after my old bike and well equipped (for £550). It dosnt have front suspension though. One local shop tried to talk me into ordering a 16 inch hybrid bike as they didnt have anything small in stock. Having tried a few bikes elsewhere, this would have been way too big for me. I remember placing my foot further back on the pedal to stop my foot slipping – far enough back in fact that the area of greatest pressure I experience when accelerating whilst standing is over the pedal spindle.
Also, one needs to keep the pedal almost normal to the pedalling force otherwise the foot will slip. I believe this is achieved by the greater ankling amplitude supported by Nick. Thus, I think that there are two factors which contribute to using a higher saddle position when not using toeclips or clipless pedals. Firstly, the foot is further back on the pedal effectively lengthening the leg, and secondly, the greater ankling required to stop the foot from slipping requires a higher saddle position. It would be very interesting to make a study of leg extension comparing these cases. I contest that it would be the This would explain why I feel most natural with the saddle-pedal distance on my old Molton noticably greater than that on my road or mountain bikes (both of which have clipless pedals). I keep telling myself to try lowering the saddle but I know it will feel cramped. Problem is it doesn’t fit well with the old safety advice about being able to put both feet on the ground while staying in the saddle of a town bike.