ETX!!! They are a rip-off. Their main business is spread betting - or ripping customers off. They clear through Macquarie who I have on very good authority have terrible support and terrible software. Try Marex in London, or may be Newedge if based in the US. We used to use Marex - they are pretty good. Fortis may also offer LME. I think TT now have LME connectivity which is good news for everyone.
NewEdge in the U.S. for sure. Advantage says they're going to get it as well, but not sure if they bought a seat or have a give-up agreement.