Éramos nosotros los que llamamos a la puerta / We were the ones who knocked on the door

Question

Hola,The sentence above was the answer to a recent question.I don't understand the need for nosotros.  Could you please explain.Muchas gracias.Saludos,Colin

Answer

Perhaps think of it as: "It was us who knocked on the door".

Answer

Hola Colin
If you consider David's translation, then you'll see it is more literal "it was us..." = "'eramos nosotros..." In this case you do need "nosotros" in the sentence.
The same goes for any other subjects if you really want to convey the same as in the English: "It is/was + pronoun..."
For example:

¡Abre la puerta, soy yo!
Open the door, it's me!
¡Fue ella la que se lo dijo a todo el mundo!
It was her who told everyone!

Saludos
Inma