Kate, who is more than eight months pregnant, will stay at home, but William and Harry are expected to be among the congregation to watch Thomas van Straubenzee marry Lady Melissa Percy.
The Duchess' final official public appearance was last weekend when she attended the Trooping the Colour ceremony with other members of the Royal Family.
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After a damp morning it will brighten up in the south and northeast but will remain cloudy in northwest England and southern Scotland.
Chinese leaders have imposed the sanctions after becoming increasingly frustrated with Kim Jong Un’s nuclear and missile tests.
Union boss says he "deeply regrets" the disruption to people's travel plans after several days of talks failed to break the deadlock.