If it is 9.00am by ET what time in London UK?

To convert the time from Eastern Time (ET) to London, United Kingdom (UK) time, you need to subtract 5 hours.

Since 9:00 AM ET is:

9:00 AM - 5 hours = 4:00 PM in London, UK.

Therefore, if it is 9:00 AM by ET, it would be 4:00 PM in London, UK.