Alice in Wonderland fans have been marking the 150th anniversary of the fateful boat trip that saw the genesis of the children's tale. But why do so many see adult themes in the story, asks Sophie Robehmed.

Alice's Adventures in Wonderland is, on one level at least, the story of a girl who disappears down a rabbit hole to a fantastic place full of bizarre adventures.

Charles Dodgson, a mathematician at Christ Church, Oxford, first told his surreal story to the daughters of dean Henry Liddell as they rowed down the Thames.

After the boating trip, 10-year-old Alice Liddell badgered Dodgson to write it down and Alice in Wonderland - under the pseudonym Lewis Carroll - was born. The heroine follows a talking white rabbit, meets the Queen of Hearts and plays croquet using flamingos as mallets.

Since the 1960s there has been a trend for readers to identify an underlying drug theme in the book.

Alice in culture Film-maker Tim Burton reprised the story in 2010 film, Alice in Wonderland, featuring Helena Bonham-Carter as the Red Queen (recreated on handbag, pictured)

Matt Groening's TV series Futurama includes occasional character Mad Hatter Bot - often seen with tea-set

Character Neo in film The Matrix told to "follow the white rabbit" - one of a number of allusions to Carroll's tales

Jefferson Airplane's 1967 album Surrealistic Pillow features White Rabbit - a song about smoking caterpillars, chess-men and mushrooms

US pop artist John Wesley's pictures Falling Alice and Humpty Dumpty in 1963 inspired by Alice stories

The Cheshire Cat disappears leaving only the enigmatic grin behind. Alice drinks potions and eats pieces of mushroom to change her physical state. The caterpillar smokes an elaborate water pipe. The whole atmosphere of the story is so profoundly disjointed from reality - surely drugs must have had an influence? After all this was the era of legal opium use.

Jefferson Airplane's 1967 psychedelic anthem White Rabbit runs with the drug theme.

"When the men on the chessboard get up / And tell you where to go / And you've just had some kind of mushroom / And your mind is moving low / Go ask Alice, I think she'll know."

The Matrix provides a film reference point. "You take the blue pill, the story ends, you wake up in your bed and believe whatever you want to believe. You take the red pill, you stay in Wonderland, and I show you how deep the rabbit hole goes."

The drug link is a homespun thing. You'll find it on a host of random forums.

But the experts are usually sceptical. Carroll wasn't thought to have been a recreational user of opium or laudanum, and the references may say more about the people making them than the author.

"The notion that the surreal aspects of the text are the consequence of drug-fuelled dreams resonates with a culture, particularly perhaps in the 60s, 70s and 80s when LSD was widely-circulated and even now where recreational drugs are commonplace," says Dr Heather Worthington, Children's Literature lecturer at Cardiff University.

Image caption Surreal scenes from the original text have made it into popular culture

"It is the deviant aspects that continue to fascinate because the text is unusual, innovative, and hard to grasp so turning to the author offers simplicity and excitement simultaneously."

The mushroom is "magic" only in the context of the story. And the caterpillar is merely smoking tobacco through a hookah.

The shadow hanging over anyone reading the story is the issue of Carroll's sexuality. A successful photographer, many of his surviving shots are of children, often semi-dressed or naked.

To many modern minds, a man who regularly formed friendships with young girls is inherently suspicious.

"Lewis Carroll's personal life intrigues adult readers because Alice in Wonderland is a text for children but the notion that the author photographed, however innocently, young girls in a state of undress is, to our modern eyes, unpalatable," says Worthington.

"That Alice was based on a child that Carroll knew adds yet another layer of interest, or suspicion, depending on how you look at it."

But Carroll was living at a time when childhood innocence was being forged, influencing how children were represented in 19th Century literature aimed at them.

Carroll's interest in young female innocence is explained by some of the experts as one that invoked desire, but not necessarily sexual.

Image caption Alice Liddell, photographed as "the beggarmaid" by Lewis Carroll

Jenny Woolf, author of The Mystery of Lewis Carroll, agrees with this theory.

"Girls offered him a non-judgemental and non-sexual female audience and he opened up to them. They loved him and he found it a relief to be with them.

"Although he was attracted to women, celibacy was a condition of Carroll's job [a condition imposed on certain Oxford academics at the time] and he believed that having sex was against God's wishes for him."

There are plenty of experts who find his interests harder to explain and it is inevitable that this knowledge will inform what readers take from the story.

Consult any set of notes on the book and you'll see a slew of themes picked out: puberty, abandonment, the challenge of transition to adulthood, even the perils of authoritarian justice in the form of the Queen of Hearts.

But bearing in mind the nature of the birth of the piece, an off-the-cuff attempt to amuse a child in a rowboat, are people guilty of reading too much into it?

Nonce and nonsense Carroll's Jabberwocky is one of the great nonsense poems in English, scattered with so-called "nonce" words - coined for one occasion only: Bandersnatch: fictional wild animal

fictional wild animal Brillig: Humpty Dumpty explains this as "four o'clock in the afternoon - the time when you begin broiling things for dinner"

Humpty Dumpty explains this as "four o'clock in the afternoon - the time when you begin broiling things for dinner" Chortled: mixture of chuckle and snort

mixture of chuckle and snort Mimsy: A combination of flimsy and miserable

A combination of flimsy and miserable Snickersnack: possibly related to large knife, the snickersnee Jabberwocky translated into French

In a recent issue of Prospect magazine, Richard Jenkyns, professor of the classical tradition at Oxford University, called Alice in Wonderland "probably the most purely child-centred book ever written" and said that its only purpose "is to give pleasure".

Yet another narrative imposed on the book is the idea of grappling with a sense of self. Carroll led a very controlled existence, struggling with self-identity, a recurring theme in the book as Alice regularly expresses uncertainty about who she is after she enters Wonderland.

"Perhaps that's why his book refers to 'morality' in jeering terms," suggests Woolf. "And the action takes place either underground or in a world which is the opposite of our own."

We can't ever truly know what Carroll intended or if he meant to write anything beyond an enchanting children's story.

Based on his own experience as an illustrator for the 1988 edition of Alice in Wonderland, Anthony Browne believes Carroll might not have been aware of the meanings found within his story.

"People interpret books in a logical way as they do dreams. They want it to have meaning. Alice in Wonderland is not to be read as a logical book. There could be some hidden meanings in there, especially considering Carroll was a mathematician during his lifetime, whether he was aware of such meanings subconsciously or not."

Ultimately, perhaps it's more enjoyable for the full intentions of the author to remain unknown during the reading of the book.

"In a way, it doesn't matter," says Browne. "I don't think Carroll wrote Alice in Wonderland to be interpreted. He wrote it to entertain."