I am a US citizen and my wife is Polish. We lived in the UK for about 8 years. I was there on a UK residence card (as spouse of an EEA citizen), although it is now expired. I worked for a company based in Liverpool. Currently we reside in Poland, where I work from home for the same company. I'm paid in pounds from the UK.
Am I permitted to enter the UK using only my US passport, let's say for 5 days, in order to meet with colleagues? I DO intend to attend meetings both formal and informal, but also while I'm there it's possible that I would perform general work duties (ie, the types of duties I perform remotely). And I'm paid from a UK source, rather than a non-UK source.
If I state my intention is to visit on 'business' and the border agent digs deeper to discover my situation...might I have some issues?
Of course, I could just state that I'm there visiting a friend and sight-seeing (true also...), but I'd rather be above board.