The lead is promising, though much of the letter is paywalled.
"Sir, I am — as he knows — an enthusiastic admirer of Giles Coren, but he
is badly misinformed about Wikipedia (“Why stop at Trump?”, Dec 12). As a
writer of history I resort to it at least a dozen times a day. I could
never have written my last two books without it, and I have never caught it
out yet, which is more than I can say of the Encyclopedia Britannica. Its
range is astonishing: it is almost impossible to find a person, place or
subject that it has left uncovered (end of my preview).... a work of
reference as useful as any in existence..."
Thanks to Johnbod for pointing this out!
http://www.thetimes.co.uk/tto/opinion/letters/article4639798.ece
Pine