Help With Plant ID Please?

The pale yellow flowered spike? I was going to weed it out a week ago, but decided to let it flower to help identify it.
Probably from a rogue seed. It looks deliberately placed in the bed, so it likely resembled a young Zinnia when I planted them all out.
It's about a metre tall. I don't recognise it, and there are none elsewhere in the garden.

Any ideas?