Thanks, I’m pretty sure it was a Cobra. But I didn’t think the white markings were normal in the Chinese Cobra or King Cobra.
It was probably far too fat for a Mangrove Snake, but I thought this species grew quite big.
You’re right about the colour. I have great difficulty with snake colour. I get an impression quickly and then remember it that way. And my mind just doesn’t think in terms of chocolate or expresso, but shades of olive. I remember calling a snake olive once only later to have it return to the house (it had been evicted once) and discover that it was a sandy-brown with red and blue flecks.