Its probably not exactly the same but this is my take on a vegan BLT. Still tastes nice even if its not quite M&S, feel free to not follow the recipe but it might point you in the right direction
3 strips Quorn bacon (or any vegetarian bacon)
3 tbsp vegan yoghurt
1 1/2 tsp nutritional yeast
1/8 tsp salt
1/8 tsp pepper
1/2 tsp lemon juice
1/8 tsp garlic powder
2 slices bread (a wholegrain one is my favourite)
Tomatoes of your choice
Lettuce of your choice (I like mixed leaves)
1 Cook the bacon in a frying pan, whilst its cooking keep turning it (I leave it on a while to make it crispier) .
2 Mix together the yoghurt, garlic, salt, pepper, nutritional yeast and lemon juice
3 Toast the bread, slice the tomato and wash the lettuce leaves. You can butter the toast if you want but I dont think it needs it
4 Spread the sauce on both pieces of toast. Put the bacon and tomato on one side, then the lettuce then the other piece of toast (otherwise the toast gets soggy from the tomato and the bread its too hard to put together)
5 Slice DIAGONALLY otherwise its not a valid BLT. Eat.