Who are the Billy Boys? Untangling the gangs and allegiances of Peaky Blinders series 5

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Here's what you need to know...

Who are the Billy Boys – and what do they want?

The Billy Boys make a spectacular debut in Peaky Blinders series five – and it looks like we're going to be seeing a lot more of Jimmy McCavern (Brian Gleeson) as this Scottish gang takes on Thomas Shelby (Cillian Murphy).

"Look down at the earth and see the seeds you have sown," warned a note addressed to Thomas Shelby OBE, pinned on a Peaky Blinders mannequin nailed to a cross and surrounded by landmines in the dramatic opening to episode two.

Tommy dodged death and saved his little boy Charlie from running across the field into danger, but the Billy Boys then declared war by murdering (and crucifying) Aberama's son Bonnie Gold (Jack Rowan), leaving another note: "By order of the Billy Boys."

And these are not the only people they have targeted so far. According to Michael Gray (Finn Cole), the Billy Boys actually approached him in Belfast to see if he would betray Tommy and join their side.

But who are the Billy Boys – and what do they want?

Arthur Shelby (Paul Anderson) gaves a brief rundown of the Blinders' new enemies: "They run every man in every coal mine, on every ship yard, east of Glasgow. Ties with Belfast. UVF. Protestant razor gang. They also dabble in politics, you know - muscle. For fascist rallies."

As for what they want, Jimmy had a simple message for Aberama: "Tell Thomas Shelby it's time to f***ing share. We'll take all the tracks out as far as Nottingham. We'll take Cheltenham as well. Otherwise it'll be Thomas Shelby who's crucified, and there will be no resurrection."

Like many of the gangs and gangsters who've made an appearance in Peaky Blinders (remember Billy Kimber?), the Billy Boys did actually exist. This Protestant street gang in Glasgow often clashed with Roman Catholic gangs in the city, and had a connection with Protestant Unionists in Ireland.

Their real-life leader, Billy Fullerton, joined the fascist party and later formed the Glasgow branch of Oswald Mosley's British Union of Fascists.

Who is Captain Swing? And who took Michael captive?

It seems the IRA would like to strike up a friendship with Tommy Shelby – though they have a strange way of going about it.

Having just survived the Billy Boys' booby trap, Tommy went back to his office and returned a call from Belfast. On the other end of the line was IRA boss Captain Swing (Charlene McKenna) from the "Occupied Six Counties" (an Irish republican term for Northern Ireland) who claimed to have identified a Peaky Blinders traitor: Michael Gray.

Captain Swing told Tommy that Michael "was in his cabin aboard the SS Monroe in Belfast dock making deals with the very men who want you dead" – i.e. the Billy Boys and representatives of the loyalist paramilitary group Ulster Volunteer Force.

They were apparently discussing "how they'd divide up the English racetracks after they've blown away your legs."

She added: "If you want we can put a bullet in his head here and now, or we can send him home and you can deal with him."

As for why the IRA would get involved in any of this, she explained: "Because, Mr Shelby, we've been informed by people at the very highest level, that since your conversion to socialism you're now on the side of the angels. And angels can be useful to us."

According to Michael, he is entirely innocent of any betrayal – having first been cornered by these mysterious men calling themselves "Billy Boys", and then marched off by the IRA.

At this point, we're still wondering: did Captain Swing truly believe Michael was in league with the Billy Boys and that she was doing Tommy a favour? Is Michael as innocent as he insists? And what will be the consequences of Captain Swing's intervention?

Is Michael a traitor?

Aunt Polly (Helen McCrory) may be convinced that her son is innocent, but a paranoid Tommy is still talking about his "black cat dream" and his fears that Michael is coming for his crown. He's even got Ada investigating whether Michael had "dealings" in America with anyone from Glasgow or Belfast.

So – what's the truth?

According to Michael, he was blindsided by two different groups of people on his way home from Boston with girlfriend-turned-wife Gina (Anya Taylor Joy).

"The ship docked at Belfast, I was then taken off the ship by two men... do you want to know the truth Arthur? Do you want to know the truth, mum? I did not betray my f***ing family!" he yelled after a less-than-friendly welcome party. "Now, mum. I want to go home."

Later, he explained: "On the journey back from New York, we got married. We needed to find a witness, a purser. He was from Belfast. We got friendly."

When the ship docked, "this purser had friends who ran a whisky distillery in County Tyrone. They wanted a way of getting their stuff into America, so I said okay, invite them aboard. When they came aboard I realised that they didn't make whisky. They were Scottish, from Glasgow. Couldn't understand a f***ing word they were saying. They started swearing, so I asked Gina to leave.

"That was when they started talking about you, Tom. They said that Tommy Shelby was a spent force. That politics had got to him. That he was spent in the head. That now was a good time to move in, and did I want to be a part of it? They knew about the money we lost in America, they said that you were going to blame me. That you had a bullet with my name on it."

As for whether he took them up on their offer, "I didn't have time to say anything. Coppers came on board. Well, I thought they were coppers –" But these newcomers were from the IRA, who got straight on the phone with Tommy to break the news of Michael's apparent collusion with his enemies.

And the first men from Glasgow? "The IRA commander said the men from Glasgow were called Billy Boys," Michael confirmed.

Jury's still out on what really happened, but the Peaky Blinders seem to have found themselves suddenly in the middle of a sectarian conflict.

What does Oswald Mosley want?

"And you prefer Irish to Scotch? As do I," mused a sinister Oswald Mosley MP (Sam Claflin) as he savoured his whisky. "Like all things regarding Ireland, it is complex, yes? Where do you stand on the Irish question, Mr Shelby?"

"I've never been asked it," said Tommy – while his "political advisor" Ada looked on, utterly unimpressed.

Oswald drawled: "Then perhaps it's time you were. We're looking for someone to begin a dialogue with certain elements in Belfast with whom we don't officially have any dealings."

In real life, Oswald had fallen out with the Conservatives over the behaviour of Crown forces in Ireland, condemning the operations of the Black and Tans against civilians and criticising government policy. It was one of the reasons he quit the Conservative party and became first an Independent, and then a Labour MP.

But he was not exactly a supporter of the IRA and Irish independence: he was more concerned that atrocities by the Crown's forces in Ireland would undermine British imperial rule and the Empire.

And anti-Catholic loyalists like the Billy Boys ultimately ended up supporting Oswald Mosley, giving backing to his British Union of Fascists.

So it remains to be seen what Oswald Means by "a dialogue with certain elements in Belfast," and what he plans to do.

"Birmingham is my concern. Ireland bores me," was Tommy's response to Oswald Mosley's overtures. But by the end of episode two, it looks like Irish politics will be central to series five – whether the Peaky Blinders like it or not....

Peaky Blinders continues at 9pm on Sunday 1st September on BBC1