Who sold insider information to the priest?

Question

In Peaky Blinders s03e06, after kidnapping Charlie, Father Hughes tells Tommy that he knows everything about his plan including digging of tunnel to steal jewels from the Russians, and the plan he hatched with the Soviet diplomat to not blow the train.

Later, Tommy confronts his family in order to know who he/she was who gave away insider information to the priest. Everybody denies doing that. Polly however believes that she might have told Ruben under the influence of wine.

At a later stage, Polly calls Ruben to their company in order to confront him (and maybe kill him as well). But they don't talk about it all. Instead, she says that she wants a normal life with him.

Who, exactly, sold the information to the priest?

Answer 1

It was Alfie Solomons who gave away the information.

"Thomas's son, Charlie, is kidnapped. Father Hughes reveals to Thomas that he knows about his subterfuge, including the tunnel into the Russian vault and sabotaging the train bombing plot. He demands the jewels as payment and for Thomas himself blow up the train - which must kill six people, in exchange for the safe return of his son. Thomas agrees unconditionally. After some investigation he discovers that Alfie Solomons divulged the plans to Father Hughes." (Source)

"Tommy then meets with Alfie asking for names of people who would buy a Faberge Egg. When Alfie gives him a list, Tommy's suspicions are confirmed as Alfie has excluded a name. Tommy had also asked for the same list from his jewelers. Tommy tells Alfie that Alfie's been working with the Oddfellows and Alfie says that he wanted to the gold." (Source)