James Callis, who played Claude Whelan in Slow Horses seasons 4 and 5, posted a picture of Lowden on Instagram, and wrote a caption supporting the star.
He said: "He doesn't need my blessing - But he's got it in spades. (Saved my life! - in the park.) #jacklowden @jack.lowden @jacklowden.fans - my word is my bond."
This come after Oldman appeared on Canada’s The Morning Show, and appeared to indicate that the casting decision of who will play Bond has already been made.
He said of Lowden: "It’s been rumoured that he’s on the shortlist. We’re going to find out pretty soon, aren’t we? Because they have picked him. They have made their choice, but they have not announced it yet. So my fingers are crossed for Jack."
It's currently unclear whether Oldman has some inside information, or is simply going off intuition.
Alongside Lowden, others rumoured to be in the running to play Bond include Callum Turner, Jacob Elordi, Tom Holland, Aaron Taylor-Johnson, Harris Dickinson and SAS Rogue Heroes star Jack Barton.
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A seventh season has also been announced, although so far the only cast member confirmed to be returning is Oldman as Jackson Lamb, with the other cast members' returns likely being dependent on whose characters make it out of season 6 alive.
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