EASTENDERS fans were baffled after Jean Slater miraculously worked out the paternity of Hayley’s unborn child – just by flicking through a calendar.

Viewers are convinced Jean now knows Alfie Moon is Hayley’s baby daddy but admitted they felt completely bemused as to how she had worked it out.

For weeks, Hayley has been hiding her pregnancy and the identity of the tot’s father from everyone.

Jean hasn’t let up however and has constantly pushed her to come clean about who the dad is.

While Hayley has laid down red herrings, Jean is like a dog with a bone and tonight appeared to have a light bulb moment.

After rowing with Hayley, she picked up a calendar to cross check dates Hayley had given her.

Then, throwing her hand to her mouth she gasped – seemingly realising that Alfie did the dirty on Kat and got Hayley up the duff.

Fans of the hit BBC One soap have known for a while and said what they found most confusing about the big reveal was how Jean managed to work it out, simply by using a calendar.

Even if it did have a massive picture of his face on it.

Another quipped: “I'm not sure how Jean put two and two together and came up with Alfie,” while a third tweeted: “How did our Jean work out that it was Alfie just by counting nine months back on the calendar and seeing a picture of him.

“I have missed something surely?”

A fourth baffled viewer asked their followers online: “How did Jean figure that out? I don't think Alfie is the only married man in Spain

“What a coincidence that January was the month on that calendar that had a photo of Alfie. A bit unrealistic that Jean put two and two together like that!”

Jean will now be forced to make a big decision about whether or not she can keep Hayley’s secret.

Can she really stay quiet and let Alfie carry on like normal? Or will she upset the apple cart and tell Kat everything?

EastEnders continues on Thursday at 7:30pm on BBC One.