No ring, no bring! Pippa Middleton reportedly banning brother-in-law's new girlfriend from attending her wedding

Pippa Middleton is set to tie the knot with James Matthews in six weeks -- and the guest list is pretty iron clad.

The Duchess of Cambridge's sister, 33, is reportedly banning her soon-to-be husband's brother, "Made in Chelsea" star Spencer Matthews, from bringing his new girlfriend Vogue Williams in light of her "no ring, no bring" policy.

Vogue, a model and TV personality, confirmed her relationship with the reality star on British talk show "Lorraine" last month.

"Pippa's view is that Vogue's relationship with Spencer is still very new. It wouldn't be appropriate for her to be there after just a few months of dating," a source told The Sun. "But some people in the circle are pretty shocked because this is her future brother-in-law who's going to end up attending on his own. It's certainly raised eyebrows."

It sounds like Pippa is pretty serious about her "no ring, no bring" policy as it also looks pretty unlikely that Prince Harry's girlfriend of almost a year, actress Meghan Markle, will be in attendance.

Royal observers expected Markle to be the exception to the rule. Besides what the beautiful bride is wearing on her wedding day, we're sure Meghan's attendance will also be another highly-talked-about topic.

"It's clear that Pippa doesn't want to be outshone by any TV babes on her big day," the insider revealed.

Meanwhile, details about Pippa and James' big day have remained under wraps.

Her sister, Princess Kate, was spotted leaving her London abode on Thursday following a bridal party summit. Kate kept it casual in black skinnies, a cozy white sweater and sneakers. The visit comes days after Kate and William dined with their future brother-in-law's family.

James popped the question in July 2016 less than a year after they started dating. He proposed with a massive sparkler estimated to cost between $198,000 to $237,000.