But as far back as I can remember, I’ve felt a deep sadness on my birthday because I knew this was the one day of the year when my birth mother must surely think about me. I’d imagine – is she counting the years?

Is she wondering what I look like, just as I’m constantly trying to picture her face? But I’d never allow my melancholy to show on my birthday.

I smiled through my childhood parties at home, and I appreciated those parties, the presents, and people celebrating the day I arrived in this world.

A day when neither my adoptive parents nor my extended family were actually present. A day they can tell me nothing about.

They celebrated my birthday every single year, but never knew the day I came into this world – never even knew of my existence.

Every year it hit me – the physicality of being born to my birth parents, yet having to pretend to celebrate being someone else’s child was sometimes too much to bear for me.

Mother’s Day has also always been a tough occasion for me. Mothering Sunday in our family was, naturally, all about Mum.

On the Saturday beforehand, Dad would take Andrew and me to the shop to choose cards. A fog of confusion and helplessness enveloped me whenever I faced this task.

I’d stare blankly at the rows of cards emblazoned with hearts and flowers and illustrations depicting perfect mother-daughter scenes. I’d see a woman in a long, flowing dress, holding her little girl’s hand as they ambled through a sunlit meadow.

Other cards declared in swirly calligraphy “I love you, Mum” and “Best Mum in the World” and other similar statements.

They used to make me feel a bit sick. They still do.

I was caught in a whirlwind of dilemmas: Which card is appropriate for me to give? For our relationship? What words do I write inside the card? I don’t quite know what to say.

Has nobody considered how difficult this is for me, knowing that I have a real mother out there … somewhere?

I felt trapped between conforming to the role of the dutiful, indebted daughter and honouring my own emotions towards this challenging day.

On Mother’s Day morning, we’d all get dressed up and go to church. At the end of the service, the children would file over to a trestle table loaded with potted primulas and we’d each choose a plant to give to our mother.

After church, the four of us would head to a restaurant for Sunday lunch. I’d play along with the merriment of the day, wishing Mum a happy Mother’s Day, masking my sadness as once again, our parents didn’t ask Andrew and me: “How are you feeling? Is today difficult for you?”

It was never, ever acknowledged – not on this day, not ever. I’d gaze around the room, consumed with silent thoughts about my real mother, looking at each blonde-haired, blue-eyed woman in turn, wondering, Could that be her?

My desire to see my birth mother’s face grew stronger with age. How I wished I had even one photograph of her. Had my adoptive parents met her? If not, had they seen a picture of her?

Then, one snowy January afternoon, soon after my thirteenth birthday, I began to fabricate a more vivid picture in my mind of what my birth mother might look like.

As I lay on my bed, reading, my hair scraped into a messy bun, Mum came in, cradling a pile of my freshly ironed clothes. Placing the bundle on the bed, she tilted her head and stared pensively at me for a few seconds. “What’s wrong?” I asked. I’d never seen her look at me this intensely.

“Nothing’s wrong, Elizabeth. I was just thinking, you’re very pretty. You remind me of Grace Kelly, actually.”

I sat up, intrigued, and surprised that she was able to connect my features to another human being. “Who’s Grace Kelly?”

“Oh, Grace Kelly was a glamorous American film star,” said Mum. “She was married to a prince.”

“Wow, a film star … married to a prince?” This was a real-life fairy tale. My mind raced. Maybe my birth mother is famous. Is she a film star, royalty even? Perhaps that’s why she couldn’t keep me – because she was too famous to reveal her secret … me.