Toning enamel colour down

[PAL]

I've  brush-repainted the top half of a BR crimson and cream autocoach driver's end end with Railmatch BR Cream enamel and it's turned out much yellower than the Bachmann cream on the sides - screamingly so. Should have tested it first, of course.  If it was an ordinary coach end I suppose I'd dry-brush it with filth-type colours to tone it down but I can't really do that here. Short of repainting with a better match in BR cream in another range, I was wondering if members with more painting experience than me can recommend any techniques for toning the yellowness down now that it's been applied  - and I suppose for toning colours down generally in similar situations. Is ultra-subtle dry-brushing the answer? If so what colours?  I don't have an airbrush.  

[57xx]

You could try a very thin wash of white or lighter cream? I've used this technique in the past to fade paint, using white acrylic and Microsol as the thinner. Any decent thinner should probably work as long as it also removes the surface tension of the water based acrylic. it's easy to remove if over-done and doesn't affect the underlying paint.