Can you tell me if this is right|: 'An exhibition of art and artefacts that illustrate how the Tudors used religion'. Shouldn't this be 'illustrates' or rephrase the sentence.

Here's what has happened:

The main text of the article reads, "Exquisite portraits, intricate statuary, rare books, lavish vestments and a unique 'Royal' bed demonstrate how the Tudors successfully used religious art as propaganda."
This has the correct plural verb.

Then someone made a 'newspaper-style' headline for the article:
"An exhibition of art and artefacts that illuminate how the Tudors used religious art as propaganda."

There is no main verb!

"...of art and artefacts that illuminate how the Tudors used religious art as propaganda" is correct because 'that' refers to 'art and artefacts', and so requires the plural verb. Perhaps the person who wrote the headline mistakenly took 'illuminate' to be the main verb.


"An exhibition of art and artefacts that illuminate how the Tudors used religious art as propaganda OPENS at the National Gallery today."
or
"An exhibition of Tudor art as propaganda DEMONSTRATES the success…."