I will elaborate, then, Nigel. Simplifying somewhat, both president's want the maximum US benefit from their trade deals. Obama's view was to deal with the biggest deals first, which puts the UK somewhat towards the back - not the absolute back of course, but fairly low priority compared to the other deals they were/are seeking.

Trump sees a bigger advantage in having the UK separate from the EU and desparate for a deal at almost any price.

Same objective, different strategies. And all about US interests, not UK.