Sorry to be a bit pedantic here, but 'marg' (margarine) has a legal definition. By law, it must be at least 80% fat, which is the same as the minimum fat content for butter. Anything less than 80% fat has to be named as "X% fat spread". If all the fat has a vegetable source, it can be named "X% vegetable fat spread". There are other (unlikely) possibilities. These legal names will usually be found in very small print on the bottom of the tub, in compliance with the legal requirement that the (true) name of the food shall be easily legible and in a prominent position(!). Ha-bl**dy-ha. The names you will see on the top of the tub - I can't believe it's not sh*te, Utterly butterly, etc don't count, since a test case for the protection of the word "butter" was lost.