Take, for example, this postcard from Elland, which was sent to Miss Ursula Prestwich in July 1927. It might not be the best example of a "picture" postcard as most of the card is taken up with a generic illustration of a bunch of heather, and Elland is relegated to a small illustration of Huddersfield Road. The card, however, dates from the 1920s and by then the great postcard boom of twenty years earlier was over, and the variety and number of postcards available was diminishing.
One might also question the absence of a stamp - this postcard has not been sent through the post. The explanation is probably that it was included with another letter or within a parcel. The message is timeless, and could just as easily be a text message or Facebook post today:-
Elland, July 23 1927. My dear Ursula, I hope you are having a good time and that you had a nice journey. Roger has been very good, but he had rather a bad night last night. With love and kisses from M and (Roger)