For the record, many people in my part of Lancashire in the UK, experienced from late November and throughout December, corona virus-like symptoms; cough, fever, breathing problems, loss of taste, etc. This pattern was repeated across the UK, as observed by a Covid symptom tracking app run by a research team from King's College London.
With or without having received a flu jab, those who did see a doctor where told they either just "had a flu virus" or, were given antibiotics to treat a throat or chest infection. Most people just had a "strange" or "troublesome" cold, and got over it. Brexit dominated the UK news agenda then, so a mystery bug would have gained little media attention.
Also at this time, the politicos would have had only the scientific evidence of the day to go on, which was, there is NO pandemic. A prognosis the British Prime Minister came to regret first hand.
As @eevblog points out, there were many international flights from Wuhan and associated cantons, including flights to Manchester, our local airport. btw Manchester, Liverpool and Preston have substantial Chinese resident and student populations.
So was Covid-19 outside of China before any official anouncement by the WHO? It would be a hard sell in my neighbourhood convincing people that Covid-19 was not already circulating in the UK before Christmas 2019.
Now all people want to know is, did I have it? An antibody testing programme would be more effective for easing the lockdown than having to rely on a "really smart" BLE phone app.