Boil the potatoes for eight minutes, then add the beans and cook for a further 3-4 minutes until both vegetables are tender. Cool, drain and place in a large serving bowl. Meanwhile, preheat the grill to medium, and grill the bacon for 4-5 minutes, turning, until crisp and thoroughly cooked. Allow to cool slightly, then cut into bite-sized pieces.
For the dressing, whisk together the honey, mustard and lemon then gradually whisk in the rapeseed oil to make a smooth and thick dressing.
Add the bacon, spinach and tomatoes to the serving bowl. Pour over the dressing, toss gently and serve.