The past perfect is used to talk about events that took place in the past, but it is different to the past simple.

The past simple is used to talk about something that happened in the past.

The past perfect is used to talk about events that happened BEFORE another event in the past.

Confused?

Here is an example:

Katie arrived at the party. (past simple)

This is where the story begins. If we want to talk about things that happened BEFORE Katie arrived at the party we need to use the past perfect.

When Katie arrived at the party, half of the pizza had already been eaten! (past perfect)

In other words by the time Katie arrived at the party another event had already taken place, half of the pizza had already been eaten.

In this sentence we start the story with the past simple and then talk about previous events with the past perfect.

1. When Katie arrived at the party (past simple), half of the pizza had already been eaten (past perfect).

Some other examples of this grammar in action:

2. When we got to the cinema (past simple), the film had already started (past perfect).

3. I called round to see David this morning (past simple), but he wasn't home. He had already gone out (past perfect).

4. I met Adam a few days ago (past simple), he had just come back from holiday (past perfect).

5. We were not hungry (past simple), we had just eaten lunch (past perfect).

Try it for yourself.

Are these sentences correct?

Bob was not at the party when I arrived, he had gone home.

My friend was very tired after a long day, so she did had gone to bed when I got home.

The restaurant was very quiet when I arrived, the other customers did had already left.

When I arrived at the bus stop, the bus had already gone.

When Claire came home her trousers were very muddy, she had played football with her friends after school.