Best laid plans...

I planned this, I really did.

Two or three move before, I visualised what I wanted, and calculated the two possibilities, and so when the below arrived I would be ready....

White to play

But it didn't happen correctly. Wrong move or move order and I was unable to recover.

I bet you, dear reader, will not make the same mistake.

Next move ? and continuation ? Honestly, it is really easy, the hard bit was seeing it before it arose !