Not that I am aware of T & M has some good advice on the topic

http://www.thompson-morgan.com/companion-planting-guide

Diane Bulley recommended one of the mallow family whose name I can never remember. A pity because I tried it and it worked. Would put a photo on if this would help.Cabbage whites do love ordinary nasturtiums but I don't know whether they would choose them in preference to cabbages.

Well the companion planting guides say that they will Stera.

Fantastic - will try it next year. Strangely they ignored my nasturtiums this year even though I kept telling them to go round the back where they were growing. Maybe butterflies are hard of hearing.

You need to have the nasturtiums right next to the brassicas, that is the only way it works. Interesting this is that the old cottage gardens were a guddle of flowers and veggies no neat rows of this and that... perhaps the old folk knew rather more than we do!

Discussed on Gardeners' Question Time in the last few days, they said it doesn't matter what you plant, the trick is to underplanting the cabbages over the whole plot so that the butterflies can't distinguish the cabbage from the soil.

Could you expand on that statement Urbanite... I would have thought the butterflies could distinguish between different plants and how do you keep the weeds under control?

Snoop, the broccoli got eaten but you didn't say whether the cabbages did?

Re underplanting: apparently the butterflies are genetically programmed to recognise the shape of the cabbage against the cabbage's natural seashore habitat. If you disguise the cabbage by putting it on a green background the butterfly doesn't see it and flies past. So you underplant the cabbages to hide the soil.
That was the theory - I always thought the butterflies could 'smell' the cabbages and the point of companion planting was to confuse the scent.
If you choose the right plants there aren't any weeds - can't recall which plants they suggested though (that bit didn't interest me!) so I'll try to find it on iPlayer.

found the GQT piece: at about 27 minutes in http://www.bbc.co.uk/iplayer/episode/b03c47gm/Gardeners_Question_Time_SettleCarlisle_Railway/