Reported in a London paper in 1762:

A bright light in the form of a straight line eight moon diameters long, one diameter wide.
I do not know if this counts as a proper UFO report, but I have in my possession a copy of The London Chronicle (also called the Universal Evening Post) dated Thursday December 23rd 1762, whose front page carries a report which I have copied and will email, referring to an obseved phenomenon at Lulworth, Dorsetshire, on December 11th, 1762, at 9pm. 
Described as "a sudden & radiant light which overspread the earth and sea, equal to the splendour of the noonday summer sun; looking directly perpendicular over us, we saw an appearance refulgent as the sun itself, in form straight as a line, about eight times the diameter of the full moon in length, in breadth not an eighth part of its length; the duration about a minute.  
Afterwards it altered its position, and changed into a serpentine form to terminate in smoke."
We express our gratitude to the gentleman who submitted the report, and for the copy of the article.  The article is written in such a manner as to make us wonder whether the event might have been the result of a meteor, but that is pure conjecture on our part.  The reference to smoke is redolent of a meteoric event, we believe.  PD