Rocha / Splash News 1 / 8
Rocha / Splash News 1 / 8

Russell Brand has only been on board the monogamy train for three months, but rumblings have already begun that the reformed Casanova is ready to commit to forever with Katy Perry.

On the heels of the couple's romantic, sledding-filled rendezvous in London shortly before Christmas, the Daily Mirror claims the scruffy funnyman, 34, has proposed to the popster, 25.

And spoiler alert: She supposedly said yes.

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"Russell knows Katy's the one for him," gushes an insider. "He's never been into a girl like he has with her, and they're besotted."

But the paper says Perry isn't quite as besotted with the spendy Cartier sparkler Brand picked out (perhaps during his Dec. 14 trip to the store, where he was photographed intently studying a diamond ring he'd slipped on his finger).

He's now said to be looking for a jewelry designer who can have a "suitable" bauble created in time for New Year's Eve.

"Katy's stylist friend and Russell's people have been quietly making inquiries for the couple so they can find exactly what they want," continues the snitch. "Katy's thrilled with Russell and how he is making so much effort. Russell also has the approval of Katy's [conservative pastor] parents, and everyone in the pair's close circle know about the engagement."

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Adds the source, "They don't know when the wedding will be, but they are planning to make it in 2010 if the schedules can work."

Further fueling the taming-of-the-Brand talk: He's decommissioned his favorite germ-laden entertaining space.

"Tonight I turned off my famous, hedonistic hot tub," he tweeted on Saturday. "A monumental event. I did it for climate change. In every sense."

Russell has also reportedly plunked down $3.25 million for a four-bedroom, four-and-a-half-bath Los Angeles estate, which comes complete with a gourmet kitchen (see pics of his new digs here).

Brand's rep didn't respond to our request for comment on the engagement report, but the comedian has become increasingly vocal about his schmoopy feelings for Perry.

"I have never felt more settled and happy," he enthused last month.

And he hinted about a domesticated future during a sit-down with Britain's GMTV a few weeks back.

When asked about marriage, Russell breezily replied, "Hmmm, that would be good." And kids? "I do want to have children. That would be good."

As for his lady-killer past, he reasons that it led him to his current blissful state.

"I thought I was promiscuous," Brand explained. "It turns out I was just thorough [to] get the right one. I'm ever so happy."

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