Matchbox Lesney 54 b Cadillac Ambulance Red Cross Decals.
This is a waterslide decal set. The first issues of the Matchbox Lesney 54 b Cadillac Ambulance had this type of decal with the red cross in the middle of a clear background. The white body colour shows through the clear. Original models will present the clear with a slight 'yellowing' from exposure.
The later issue models in regular wheels and the Superfast version used a white vinyl sticker.
These are water-slide decals. Clean your model first. Soak the decal in a shallow bowl or saucer until the decal can be separated from the backing paper. If the decals are multiples do one at a time. moisten the location on the model where the decal will be applied. This will help get in on the model and adjust before touching gently with a dry sponge to remove excess after correct positioning. Leave to dry.