Warning: minor spoilers for the Season 4 finale of Downton Abbey

As Season 4 drew to a close, Downton Abbey continued its grand tradition of having its fictional characters run into real history. In this case, that history involved the very highest level of English society: the royal family.

(MORE: Catch up with TIME’s recap of the Downton Abbey season finale)

On the show, Lady Rose has the opportunity to rub elbows with the Prince of Wales — the future King Edward VIII, who eventually came to the throne in 1936 — and his lover, Mrs. Freda Dudley Ward. The story’s main arc is set into motion when a letter from the Prince to Freda is stolen by a no-good card sharp hanging around the Crawleys. If he leaks the letter to the international press, it could cause a scandal, which sends Rose and Robert into detective mode.

As it turns out, there was correspondence between the Prince and Freda — as described in the book Letters from a Prince: Edward, Prince of Wales, to Mrs. Freda Dudley Ward. The socialite daughter of a rich businessman, she was already married when she met the Prince, but her marriage wasn’t in good shape. In 1918, the Prince began to send her the first of what would be many letters.

Though their romance ended abruptly in 1934 when the Prince began his relationship with Wallis Simpson, the woman for whom he would eventually give up the throne, the Prince of Wales didn’t exactly hide his feelings. Take, for example, one missive from June of 1919: “Darling darling beloved little Fredie,” he begins, “This is only just a teeny weeny little scrawl to catch the last post sweetheart and to tell you how fearfully madly I’m loving you this afternoon angel and looking forward to 4:30 tomorrow. Although I only said all this about 12 hrs ago I can’t help saying it all again this afternoon only I mean it even more sweetheart!!”

His affections are certainly potent. The letters also make clear the weakness of his knowledge of comma-usage standards (and his occasional tendency to refer to himself in the third person, which, ick) — but that didn’t diminish their value. Far from it: in 2003, more than 300 of those letters were offered at auction with an estimated value of up to $150,000; another single letter, sold last November, fetched a value worth more than $8,000.

Write to Lily Rothman at lily.rothman@time.com.