A nice little piece Simon. Pallets from abroad are often made from beautiful timber because it is plentiful where the pallets are made so it pays to check.
99% sure the wood is mango. It varies from off white through grey to brown and black and all shades in between. It spalts easily. Most often found in pallets from India where the trees are cut down and the wood used after their fruiting years are over.
I agree that it is mango. Coincidentally I posted a picture of a Knurl GT pen in curly Mango today and it looks very similar.