What is this?

My first instinct was to say that it's a species of hoverfly that I haven't seen in our garden before, but when I tried to match it with various pictures of types of hoverfly I couldn't find an exact match. There was one that was similar, but not exactly the same so I'm doubtful that is what I have photographed.

Therefore this is a cry for help.

Can anyone identify what this is? Is it a hoverfly and if so which type? If it's not a hoverfly then what is it?

As you can see it has two large antenna coming from a single point in the middle of its head/face which suggests to me that it is not a hoverfly as the others I have seen don't have these. It has a long thin body, which is black with yellow bands running round the body. It has large eyes and its face below these is yellow. It also has two yellow spots, one on each side of its thorax, which is all black apart from these two spots near the head.