Which is how, later that day, Grandpa Byron and I end up in Blaydon, fifteen miles up the Tyne from the coast, and I tell you: fifteen miles on the back of a little moped is enough punishment for anyone’s bottom.

Grandpa Byron’s been telling me that when he first came to the UK, Blaydon was a coal-mining village, but there’s no mining here now, just street after street of neat, red-brick houses, and a supermarket, and a garage, and it’s just like everywhere else really, except it’s up one side of a valley and in some places you can see right down to the river Tyne and across the other side, and that’s pretty cool.

And that is where my mum, Sarah, lives, on a wide road outside of Blaydon. Grandpa Byron’s already phoned her to tell her he is coming. They stayed in touch for a while after her near-drowning; she invited him to her wedding (to Roddy, a policeman) but he didn’t go, and then they kind of drifted out of each other’s lives. But, as Grandpa Byron pointed out, it’s difficult to hide these days, unless you really want to, and it didn’t take him long to track her down.

The trouble is, of course, that my mum is only my mum in another – and I’m sorry, I’m going to have to get technical here – spacetime dimensional thingy. She’s not my mum here, a fact I’m not completely sure Grandpa Byron has understood (and who can blame him?). Quite what he’s thinking I don’t know. I don’t actually think he’s worked it out beyond, “A boy needs his mum.”

Now we’re outside her front door and even though Grandpa Byron has told me to be calm and not to freak her out, when she opens the door, she is exactly, exactly my mum, even down to the way she’s wiping her hands on a tea towel, and something in me just pulls me forwards and before anything else happens, or any other greetings, I just say, “Hi, Mum!” and wrap her up in my arms, and I just know at that moment that the most powerful force in the universe – a parent’s love – will make her see the truth, and she’ll know that I am her son, and she’ll fold her arms around me, and kiss the top of my head, and say, “I’ve missed you, Al. All my life, I’ve missed you, and now you’re here,” and everything will be all right.

Except she doesn’t. And it isn’t.

It is awful. She kind of gently eases herself out of my arms, and holds on to them and looks into my face and says, “Er … OK?” and I say, “Mum?” and I know I’ve blown it.

She’s totally freaked out, though she’s kind enough not to make it obvious. Her eyes flick to Grandpa Byron; she’s still holding my arms at my side so that I can’t hug her again.

“This is, ah …” begins Grandpa Byron. “This is my grandson, Al Chaudhury.”

Mum lowers her head and looks in my eyes and says, a bit slowly, “Hello, Al. Nice to meet you.”

Of course. She thinks I’m slow, or have some sort of mental disability, and why wouldn’t she?

So begins the most awkward, uncomfortable fifteen minutes of my life. Or – to adapt the hot stove/pretty girl analogy of my namesake Professor Einstein – “fifteen minutes in the presence of someone who both is and is not your mum, along with her suspicious husband, feels like a lifetime.”

We go through, me and Grandpa Byron, and we sit in her tidy front room, and her husband Roddy, who’s now an inspector in the Northumbria Police, brings tea, and a juice-in-a-box for me, like I’m five or something. She and Roddy and Grandpa Byron talk adult small-talk, all the how-have-you-beens and everything, which lasts a few minutes, and I learn that she and Roddy have no children, but several nieces and nephews that they’re very fond of, and they moved here about eight years ago, and Roddy built the conservatory himself, and blah blah blah … but then it starts to get a bit tricky because all this while, I have said nothing and there are some big question marks hanging in the air. Who am I, why did I call her ‘mum’, and so on.

Mum says to Grandpa Byron, “Did you say Al was your grandson? By your daughter, Hy … er …”

“Hypatia. Yes.”

“Didn’t she move to America, or Canada, ages ago?”

“Ah. She, er, she came back.”

Then Roddy chips in, “And he has your surname? Chaudhury?” Perhaps it’s just me, perhaps it’s just because I’m on edge and he’s a policeman, but there’s an almost-silent suspicion in his voice.

“Yes. We wanted to keep the name in the family,” says Grandpa Byron, airily. Too airily, if you ask me, because there’s still something going on in Roddy’s eyes.

And me? I’m sitting there, saying nothing at all. I mean, I can’t, can I? What can I possibly say? It just can’t get any worse.

(By the way, whenever anyone says that to you, remember that it will get worse. It did for me, and it was all my fault.)

I’m on her shiny black sofa, and there’s one thing I can do to show her that we have a connection, that might persuade her that she is my mum, and that’s my syndactylic toes. I wait till Roddy’s left the room for a moment, then without saying anything I quickly take off my shoe and sock and say, “Look!”

(Another tip: if you’re in strange company and want to convince someone beyond doubt that you are mentally deranged in some way, taking off your shoes and socks and saying “Look!” is a good way of doing it, I now know.)

Mum barely glances at my feet, but smiles indulgently and a bit nervously, and her eyes look at Grandpa Byron, sort of pleading for help.

“My toes!” I say. “Syndactylic! Like my mum’s.”

“Oh yes!” says mum enthusiastically, but it’s not her real voice. It’s the voice that people who don’t have children use when they talk to children. A bit too sing-songy. “Did your Grandpa tell you I have that too? You probably know how rare it is! How unusual! You’re very special, Al, aren’t you?”

Special.

Mum’s smiling at me, but it’s not a real smile either. It’s a sympathetic, synthetic smile, which might be all I will ever get from her.

It’s time to go. I can’t stand it any more, and I quickly put my shoe and sock back on and stand up as Roddy comes back in the room.

Mum says, “From your mum, you say?” Then to Grandpa Byron, “I don’t remember you saying Hypatia had syndactyly?”

“Ah … he’s confused, bless him. He means his dad. Anyway, nice to see you again, Sarah, Roddy,” and it’s like we can’t get out of their house fast enough. I know that I’ve been acting oddly, and there’s just this look that is still on Roddy’s face as he and Mum say goodbye, and “please come again!” and all of that. I know I have messed up, but still I try one more tactic.

“Say hi to Aunty Ellie for me!” I say, and Mum gets this shocked look on her face as Grandpa Byron practically pulls me up the driveway.

Back on the scooter, we are a little way up the street, and I crane my neck back to see Roddy turn to Mum. He purses his lips and shakes his head, and it’s at that exact moment that I can see what’s coming, and I know what I have to do.