I've never quite recovered from the shame of being asked, "What's your favourite Beatles album?" and replying, "Er, the red and the blue one?"

Well I was only 10 at the time. How was I to know there were more than two Beatles albums?

And back then the only record I actually owned was Remember You're a Womble.

The rest of my musical education was based on what was blasting out of my older brothers' bedroom.

Usually Sassafras, sometimes Rush, and if the cacophony happened to be Deep Purple I ran down the stairs with fingers in ears.

This vicarious introduction to the sounds of the '70s could also be very confusing.

I remember them having Band On The Run for Christmas and wondering why Michael Parkinson had joined Wings.

By the time I got to secondary school, my disengagement with the musical zeitgeist continued.

While the glam girls chalked I Heart Duran Duran on the blackboard and the cool girls hid behind fronds of giant fringes listening to The Cure on their Walkmans, I spent my spare time playing flute solos with Llantrisant Male Voice Choir.

This was far more fun than it might sound but it didn't exactly enhance my musical kudos with my peers.

While they celebrated their 18th birthdays at Gingers nightclub in Pontypridd, I shared mine with 50 old chaps of pensionable age on the bus back from 1,000 Voices at the Albert Hall.

What can I say? Give me Gwahoddiad over Primal Scream any day.

Not that I missed out on the '80s entirely. I did don a jade flying suit and head to St David's Hall to see a live band for the first time aged 14.

It was Orchestral Manoeuvres in the Dark, the geography teachers of New Romanticism whose name was far harder to spell on the board than Duran Duran.

They only had two hits - both about Joan of Arc, which suited my Catholic schoolgirl sensibilities. I loved French saints. My confirmation name was Colette.

I queued for their autographs and they signed my handbag.

This felt like a vaguely teenage musical experience for an adolescent as square as me. But OMD never really made me go OMG.

So much of '80s music seemed to be about fashion rather than feelings, and very little of it spoke to my inner pubescent drama queen.

So I bought a guitar in Cardiff's Gamlin's music store and took refuge in the folk rock of a previous generation - Carole King, Judy Collins, Neil Young, Cat Stevens, Nick Drake, Simon & Garfunkel, Joan Baez, James Taylor... anyone, in fact, who could perform a song without the need for eyeliner, frilly shirts and a Casio keyboard.

But in the realms of the acoustic singer-songwriter, one artist strummed my teenage heartstrings more than any other - and with fancy open tunings too. Joni Mitchell, of course.

Poet, painter, visionary. Finally, I had found my musical muse.

In my post A-level summer - that slightly dreamlike hiatus between school and university, childhood and adulthood - I lay on an Italian beach, switched on my Walkman (Aiwa, not Sony) and immersed myself in Joni's lyrical world.

On the sands of Lido di Jesolo, I aspired to be this free-spirited woman of heart and mind on the journey of self-discovery she described in her song All I Want:

"I am on a lonely road and I am travelling
Travelling, travelling, travelling
Looking for something, what can it be?"

But any hope of wild European adventure was scuppered by the presence of my parents, snoozing on nearby deckchairs.

My school pal Philippa and I had tried to persuade our respective mams and dads we could go it alone that summer but they were having none of it.

My folks did their best to keep a loose leash but it only took one pervy waiter paying us unwelcome attention to prompt my mother to swoop into action like a Victorian chaperone.

It didn't matter. When it came to learning lessons in love and life, what I lacked in practice I was gaining in theory by listening to Joni's seminal album Blue.

This was a crash course in soul-stripping with a diploma in raw emotion.

No wonder it became the standard by which all confessional songwriting is judged.

Pain and passion. Hope and despair. Ten tracks that exposed the most intimate thoughts about unravelled relationships and how love could be both toxic and intoxicating.

They weren't just about break-ups, they explored the relationship with oneself, a search for purpose and meaning on a literal and figurative journey where both wanderlust and homesickness co-existed.

And they appealed to the head as well as the heart.

The sheer craft of the songwriting was mesmerising. The beauty of the melodies and unexpected harmonies were laid bare by the simplicity of the arrangements, sometimes nothing more than a guitar or dulcimer.

Or piano. Has the chill of winter and a lonely Christmas ever been evoked so powerfully by the stark opening chords of River, with its dark riff on Jingle Bells?

The lyrics painted images as striking as those Joni committed to canvas in her parallel career as an artist, like A Case of You, for example: "You're in my blood like holy wine, you taste so bitter and so sweet. I could drink a case of you and I'd still be on my feet."

And despite the deep dive it took into dark nights of the soul, Blue was not bleak.

There was joy and adventure too, songs that raised a smile like the humorous hiraeth of California which sees Joni sitting in a park in Paris, France, meeting a redneck on a Grecian isle and staying in Spain till her skin turns brown but all the while dreaming of coming home to America's West Coast.

Then there was the plaintive ache of missing someone, expressed so perfectly in My Old Man: "The bed's too big/the frying pan's too wide."

All these thoughts, feelings and ideas were communicated so distinctively in a voice like no other. Joni's voice was saved from folk sweetness - and blandness - by that sharp warble in its upper register. Piercing, but in a good way.

In the summer of 1987 I'd never heard anything like it.

When Blue was released in 1971 they hadn't heard anything like it too.

Joni's peers were startled and even disturbed by its unflinching emotional honesty.

Her friend Kris Kristofferson's response to the album was, apparently: "Joni! Keep something of yourself!"

But Blue unpacked universal experiences through the prism of this remarkable songwriter's personal pain and pleasure. As she explained herself: "If you listen to that music and you see me, you're not getting anything out of it. If you listen to that music and you see yourself, it will probably make you cry and you'll learn something about yourself and now you're getting something out of it."

This quote was played at the close of a BBC Radio 4 documentary this week to celebrate the 50th anniversary of Blue.

It was presented by Laura Marling, the latest in a long line of artists - from Prince to Bob Dylan - to acknowledge their debt to Joni Mitchell.

As Marling outlined the life events that found expression in Blue - including the heartbreaking decision Joni made as a penniless young single mother to give up her daughter for adoption - I listened to the album once more.

Had it dated? Did it belong to that post-A-level summer of adolescent angst and wonder rather than the more prosaic emotional landscape of middle age?

I braced myself for disappointment.

But as those first chords worked their open-tuned magic, the spell was cast once more.

A heart that's known sorrow and joy since those tender teenage days found new resonances in these timeless songs. I've looked at Joni Mitchell from both sides now and she's still the best.