For the person seeking MG magazine advertisements.
MG advertised rather heavily in the car mags, like Road and Track,
Sports Cars Illustrated and Sports Car Graphic in the 60's and 70's. Lots
of MGB & Midget ads, plus quite a few for the MGA.
MG also ran full page MGB ads in Playboy and Penthouse mag during
the 60's, not sure if they continued into the 70's.
MGB ads can also be found in Time magazine from the late 70's.
There are a couple of T's shown in Coca Cola ads in National
Geographic during the 50's.
I agree with the comment that it is really cheaper to buy the ads
cut out and offered by a dealer. I can usually find B ads for $1 in black
and white, $2 for color. A ads run around $3 and T ads run higher. For
pre-war stuff you will have to look for British magazines. Hopes this helps.