What you have looks more like late blight than early blight to me... early blight has a different pattern and coloring of the lesions. See link below and click on the photo that looks like your leaves; for a photo of early blight, click on the photos in the top left grouping; when you get to the next page, click on the photo in the lower left of that grouping.

My experience with either kind of blight is that they're difficult to control or slow down. If you don't mind using chemicals, be sure to use ones that are labeled for use on tomatoes. Something that isn't labeled for them may be something that stays in the plant and could be harmful to anyone who eats it. There may be some organic fungicides you can mix up, too -- if you're interested in that, google it, or try posting on the organic gardening forum. I seem to remember something about fungicides made out of baking soda? or something -- don't take my word on it, however :) but I'm sure there are organic solutions. May be easier for you to find/make one of those than find the chemicals you need. Also keep in mind that fungicides may need to be applied regularly to be effective -- at least until some drier weather hits!

I always mulch my tomatoes, usually with newspaper and straw, because in my experience I had less disease problems that way... had the most problems when I was facing the cold, wet weather you're describing.

Here are a few suggestions on blight taken from a website -- some of these things I know are out of your control at the moment

* Keep foliage dry: Locate your garden where it will receive morning sun.
* Allow extra room between the plants, and avoid overhead watering, especially late in the day.
* Purchase certified disease-free seeds and plants. There are no late blight-resistant tomato cultivars.
* Destroy volunteer tomato and potato plants and nightshade family weeds, which may harbor the fungus.
* Do not compost rotten, store-bought potatoes.
* Pull out and destroy diseased plants.
* If disease is severe enough to warrant chemical control, select one of the following fungicides: chlorothalonil, fixed copper, maneb or mancozeb. Follow the directions on the label.

Keep your fingers crossed on the Bali tomato! And good luck!

Here is a link that might be useful: tomato diseases

Thanks for your response carol_ann, I had posted the same message on the Tomato Growers forum and there had been a fair bit of back and forthing going on and I have received some feedback which has been very interesting. I too thought it might be late blight, but since the first signs appeared over two weeks ago, I have been told that the plants would have all died by now, yet they are still growing (though leaves are still slowly turning brown). Anyways, check out the other discussion if you are interested... Thanks

Jamie

Here is a link that might be useful: tomato forum thread