Credit: © Copyright ITV plc 2013

Downton Abbey’s Lady Mary Crawley (Michelle Dockery) has a bit of a reputation for being a black widow, and yet her notorious love life doesn’t seem to keep the men away. We only met Lord Gillingham (Tom Cullen) in the January 12 episode but it was pretty clear Tony was crazy in love with Mary. But despite the obvious chemistry between these two, even we were shocked when Tony put all of his cards on the table and proposed to Lady Mary in the very next episode.

After a little strategic planning on the part of Mary's mother and her aunt, Lord Gillingham is invited to join the party of visitors from Downton during a trip to London. "I hope I'm a surprise, not a shock," he coyly tells Mary upon dropping in. This chap just seems full of surprises; Tony even gets Mary to dance when the group heads to a jazz club.

While out on the dance floor, Mary tries to explain her feelings to her obviously ardent suitor. It's been lovely spending time with you, she tells him, but whatever may be blooming between us must stop. After all, Tony is engaged. "Almost engaged," he quickly corrects. Still, "almost engaged" is good enough for Mary who, beyond that obvious hurdle, does not feel ready for love after the loss of her beloved Matthew (Dan Stevens).

Credit: © Copyright ITV plc 2013

This session of straight talk does little to discourage Lord Gillingham, however. Unable to see Mary in London again before she returns home, Tony hops the same train back to Downton. Once arrived, he gets right to the point: "I've made a long journey to ask a very short question." Um, excuse us?! Is he proposing? 

As the practical Mary points out after Tom's bold move, they’ve only known each other for several days. Tom counters that they’ve technically known each other since they were children. That's true and after sharing how great his feelings are for Mary, even the notorious ice queen finds herself melting. She doesn't give him an answer right away — partially because of some badly timed interruptions by Jimmy Kent (Ed Speleers) and the Daddy Grantham (Hugh Bonneville) — and so for a fleeting moment it seems Mary may have found a new partner.

Flash to the next day and Mary and Tom are out walking the grounds. He asks if she has an answer for him. "If you do not want me, I feel honor bound to go through with it," he says of his potential engagement to the Hon. Mabel Lane Fox. Conflicted, Mary admits she's just not ready to remarry. "You said yesterday your brain is full of me," she explains. "Well, mine is full of Matthew." And she cannot bear to part with him. Yet.

Credit: © Copyright ITV plc 2013

Gallant as always, Tony makes a graceful exit but not before asking Mary for a memento of their time together: a kiss. And what a kiss it is, so passionate that for half a heartbeat we almost expect Mary to call out after Tony as he walks away, presumably to marry Mabel Lane and never return to Downton. But the always reserved lady does not change her mind, only alluding to regret when later speaking with Tom Branson (Allen Leech) about a recent choice she's made: "I have a sneaking fear I may regret [my choice] for a long time to come."

Luckily for Mary (and us), Gillingham isn't gone for good! He'll return later this season in the February 9 episode where he notices a war buddy of his taking a particular interest in the woman he loves. By this point Tony's engaged to the Hon. Mabel Lane Fox but it's obvious he's still madly in love with Mary. So in love, in fact, that by the very next episode he's decided to call off his engagement and spend his life in pursuit of the eldest Crawley daughter.

"I won't give up, not until you walk down the aisle with another man and perhaps not even then," he tells her. Will his persistence pay off? There's no telling with Mary even after the Season 4 Christmas Special, airing on PBS on February 23.

What do you think of this particular romance? Should Mary say "yes" to Lord Gillingham, stay single, or wait for another handsome suitor? Share your thoughts in the comments below.

Elisabeth Kramer is an Assistant Editor at Wetpaint Entertainment and our resident Downton Abbey expert. Follow her on Twitter and Google+!