JK Rowling has upped the ante in her Twitter war with Piers Morgan with her latest post, carefully setting a trap which he walked right into.

The Harry Potter author dug out a fawning article which praises her for inspiring children and refusing to "play any part of the celebrity game". It added: "Ms Rowling definitely matters."

She wrote along with a screenshot of the article: "Just been sent this! Could the writer let me know who he is? I'd love to thank him!"

Morgan was quick to respond to Rowling's tweet, saying it was a "priceless humblebrag".

Rather hilariously, he didn't seem to remember that the quote is from an article he wrote for the Daily Mail in 2010, titled 'The 100 British Celebrities who really matter'.

So it seems Rowling's secret admirer is Morgan himself.

Previously, a London bookshop stepped into the ongoing twitter spat between the pair, which originated over Morgan's support of Donald Trump, by trolling him in the most perfect way imaginable.

The Harry Potter author expressed glee on Twitter at the broadcaster being sworn at by Australian comedian Jim Jefferies after Morgan refused to call President Trump's travel ruling a Muslim ban during an appearance on a US talk show.

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Rowling wrote on the social networking site: "Yes, watching Piers Morgan being told to f*** off on live TV is *exactly* as satisfying as I'd always imagined."

Morgan wasn't exactly thrilled at her comments and wrote back saying he'd never read any of her best-selling books.

"This is why I've never read a single word of Harry Potter", he said, prompting a bitter battle of words between the pair.

Now North London's Big Green Bookshop has entered the row and has started tweeting Harry Potter and The Philosopher’s Stone word-by-word to Morgan.

The entire project will take 32,567 tweets to complete - at the moment they're just 236 tweets in.

Rowling previously reminded Morgan of a past triumph she had over him.

JK Rowling with Emma Stone and Eddie Redmayne at the BAFTAs

Before she attended the BAFTAs in London on Sunday, she tweeted a screenshot of an old article that reported how her sixth Harry Potter novel - Harry Potter and the Half-Blood Prince - beat Morgan’s autobiography to be named book of the year at the British Book Awards.

Alongside the photo, the author added the hashtag #StillHurts.