This could be tobacco mosaic virus [tmv].
The lack of colour could be due to lack of nutrients, a dose of Epsom slats would not hurt. if it is mineral deficiency then they will green up. If not then it is likely to be tmv.
see what others think. if it is tmv then dispose of them by burning or in household waste not in the compost bins.

Ok thanks i will try epsom salts first

I think it's definitely TMV thanks for pointing that out i think your bang on. I read up bit on it and it says infection can start from bruising and brushing past the plants which is exactly what i did. I pinned back a path to the rear of the garden as the plants grew at such speed they blocked the pathway thru the garden and the plants that are most affected are at the ones at the edge of the pathway. I have somehow unwittingly got the virus on my jeans and spread it and now the other tabacco plants i planted elsewhere have been infected. Nothing else seems to have been infected so next year i will plant something non related there and try the tabacco again but in places where they will be undisturbed and see how i get on.