Thanks guys for the help. I just used the flip function (quickly at work) and it seems to do the job.

Regarding the way I have modelled it, I have a habit of lofting/networking halves of objects then mirroring & joining, perhaps not a good practice? Model is joined as I have found that light gaps occur between surfaces unless they are joined prior to polygon export.

I think my materials in Kerkythea are a bit of a mixture of double and single sided. This model will need to be imported into MAX and I want to be certain that when it is it will render correctly regardless of how materials are applied.

Thanks everyone for the help. It is greatly appreciated :)