William Shakespeare was in fact Edward de Vere, the 17th Earl of Oxford, and is buried in Westminster Abbey, not the Holy Trinity Church in Stratford-upon-Avon, according to a scholar who is the grandson of the novelist Evelyn Waugh.

Alexander Waugh says he has deciphered encryptions in the title and dedication pages of Aspley’s edition of Shakespeare’s sonnets of 1609 that reveal the bard’s final resting place.

He will present his evidence at a conference at the Globe theatre in London on Sunday, where the audience will include the actors Sir Derek Jacobi and Sir Mark Rylance, who are fellow anti-Stratfordians - long-standing doubters that Shakespeare wrote the plays and poetry that bear his name, and whose preferred authorship candidates include De Vere.

Waugh said he would show hidden geometries, grid patterns and other clues which reveal that Shakespeare’s final resting place is underneath his 1740 monument in Poets’ Corner at Westminster Abbey and that they spell out the words “Edward de Vere lies here”.

He said he had “finally decoded the mysterious dedication” to the sonnets. “Stratfordians and anti-Stratfordians have said that this dedication page must be encrypted, because it doesn’t seem to make any sense. It’s got those funny dots all over the place and there’s something very weird about it. I’ve finally cracked it.

“The title page and dedication page have encrypted in them the exact church, the exact part of that church and the exact spot … where Shakespeare is buried. It’s like an old-fashioned treasure island map. You overlay the title page on to a ground plan of Poets’ Corner and it just points to exactly where he’s buried. It’s just phenomenal.“The dot marking the burial place on the title page landed on the exact spot where, in 1740, the famous monument to Shakespeare was erected by Alexander Pope and Lord Burlington, a direct descendant of Oxford’s sister, Mary Vere. It strongly implies that the people who put that statue there in 1740 knew damned well that he was buried right underneath it.”

Noting that the Church of St Peter is Westminster Abbey’s correct title and that Poets’ Corner was known as South Cross aisle until the 19th century, Waugh said: “At the Globe, I will show how the dedication, when rearranged like a crossword into a grid, reveals the message ‘To the Westminster at South Cross Ile, St Peters, Edward de Vere Lies Here’.”

He laid out the text into an equal-letter spacing grid, “a popular form of encryption in the 15th and 16th centuries … looking for messages that appear in the vertical columns”.

“People have been trying to do this for ages. What I worked out was, don’t just look in vertical columns for words going vertically downwards. Look for shapes. That changed everything … The messages were in crosses, shapes and rebuses.”

Waugh was led to the encryptions by what he describes as “a riddle” in the Shakespeare monument in Stratford. He argues that it alludes to Shakespeare’s burial alongside Beaumont, Chaucer and Spenser, who are buried “in precisely that order” in Poets’ Corner.

The sonnets’ dedication, like the text on the Shakespeare monument, is “gibberish” until one deciphers its hidden messages, he said.

Westminster Abbey’s website states that Shakespeare was buried in Stratford: “Shortly after Shakespeare’s death there was some talk about removing his remains … to Westminster Abbey, but the idea was soon abandoned.” Waugh argues that Ben Jonson described Shakespeare in 1623 as “without a tombe”. De Vere died in 1604 and was buried in Hackney, east London, but his first cousin noted – in a manuscript in the British Library – that he now lay buried in Westminster.

“So there’s always been this thought that he was reinterred in Westminster. I went to the Westminster Abbey archives. They said, if anyone’s reinterred, we don’t have a record of it.”

Waugh added that the Stratfordians would have loved this discovery. “But it tells you that it’s De Vere, so they’re going to hate it.”

Since the 1850s, dozens of candidates have been suggested as the likely author of Shakespeare’s writings. In 2013, leading academics contributed to a major publication, Shakespeare Beyond Doubt, to prove he really did write his own plays and poems, apart from his collaborations.

Its co-editor, Paul Edmondson, an expert from the educational charity Shakespeare Birthplace Trust, said: “These theories just seem to get more and more fantastic and take us into the realms of science fiction and fantasy novels. This has always been part of the fascination of those who are seeking to disprove authenticated history.”

• This article was amended on 30 October 2017 to include Sir Mark Rylance’s title.