From the LEL 2017 website:
"Overseas residents must arrange their own third party insurance.
"When you register on 29 or 30 July 2017, we will ask you to sign a written declaration that you have at least £1 million of third party insurance cover. If this level of cover is not available where you live, please contact us."
I understand this is liability insurance. I have yet to find a UK insurance source which sells cyclist liability insurance to non-UK residents.
As a US resident / citizen, I understand (at least that's how it was handled 8 years ago) that my US automobile insurance policy covered me when operating a rented motor vehicle in the UK.
Over here, one's home owner's (or renter's) insurance, if it covers liability, covers whatever I might perpetrate on a bicycle.
I will ask my insurer if this stretches across the ocean -- but, would be interested in hearing from others how they are planning to handle this.
Does LEL have any specific coverage text in mind? [ An insurance broker friend of mine used to say "our policies cover you 100% unless you are alone or with someone" ]