It will be the variety you bought, there are yellow, burgundy and red cherry tomatoes - just look in your local supermarket or green grocers if you are lucky enough to still have one.

Yes, I grew these a couple of summers ago but didn't have much luck. One of my daughters once cooked blue potatoes for Christmas dinner, they looked strange but tasted normal with your eyes closed!

It looks like the variety 'Chocolate Cherry'. In my experience, the purplish tomato varieties tend to be among the tastiest. My favorite is 'Cherokee Purple', closely followed by 'Black Krim'.

Thank you all for your responses!

we have grown a rosy pink coloured one called Rosella this year. it tastes amazing.