Knee length coat solution

[aarghhelp]

I now have 4 - four! - knee length dresses for work, after being convinced by the arguments for finding a non-frumpy length. However, I have been going through lots of size changes over the past year or so. 1 M & S coat I have that does fit is 3/4 length, so great with trousers but not with my shirts or dresses.I like this but wonder if it is not warm or durable enough. I don't like the look of their other velvet coat.

Think that coat is more evening wear than for work? How about a knee length mac - lots of places doing them, Unless you are walking to work/waiting at bus stops you won't really need a very warm coat