[cfgvjkljhgfb]

He was on a visa waiver - if he is British that allows him to do anything you can do on a B1 business visa. In fact the only reason you have to get a B1 visa is because you can't use the visa waiver if you are, say a convicted criminal!

You can work for your outside-the-US employer, you can collaborate with US customers, suppliers, partners, you can train them,you can sell, demonstrate and install products. About the only thing you can't do is work for a US company.

Picture if he was an engineer from Rolls Royce aero engines going to Boeing - everything that engineer might need to do you can do on a visa waiver.

[nandemo]

Indeed, but if you're self-employed, then you should either say you're coming from (your own) Foo Corp. in Australia to have business meetings with Bar Corp (in US); or follow GP's advice and say you're on vacation.

[dedward]

Despite your visa waiver, you still have customs forms to fill out and they do ask whether or not you are on business or not. They're very clear that having a waiver, or even a visa, is not a guarantee of entry into the US and that ultimately it's up to the CBP agents.