Non-defining relative clauses

Non-defining relative clauses give extra information which is not essential about the noun that they follow. If we remove the relative clause, the sentence still makes sense.

This sentence is already complete, but we can add extra information to it in a non-defining relative clause.
Walter Turnbull has just passed and A-level in Spanish.
Walter Turnbull, who is 81 years old, has just passed and A-level in Spanish.

We cannot omit the relative pronoun from a non-defining relative clause (His teachers at Lancaster College, where he took the exam, are delighted).

We always use commas to separate the non-defining clause from the rest of the sentence (Walter, whose grandaughter Tess also did the exam, now has 39 A-levels!).

We can combine two simple sentences by using a non-defining relative clause.
Jaime's sister is called Pilar. She's a teacher.

• Jaime's sister, who's a teacher, is called Pilar.
• Jaime's sister, who's called Pilar, is a teacher.

Remember!

• We never use that ina non-defining relative clause.
• We always use who or which.