That’s what I was going to say. If he wants a nickname, he could be Will, Bill, Liam, etc. It’s pretty customizable.
Or, Jeremy, or Philip.
Interestingly I see nobody has yet suggested:
Michael
But you could also go with my own name, which has become increasingly rare these days and it would be good to see make a comeback:
Paul
Oh no, really?
Henry is my 5th favorite boys’ name. It comes in after Nicholas, Owen, Christopher, and Jeremy.
Gregory
I always liked Christopher. But being Jewish, I couldn’t use it.
Eric, Kevin, and Brian are nice solid names that aren’t being used too much these days.
What’s your ethnic background?
Some of my favorites are:
Charlotte, Eleanor, Serena, Moira, Claire, Lucy.
Benjamin, Nathaniel, Oliver, Gabriel, Theodore, David.
Wyatt. Need I say more. No finer male figure than Wyatt Earp.
Maybe Garrret.
I have a sweet niece named Katie. One of the finest children I have ever encountered.
Is that the pirate version?
Well, the naming “style guides” recommend mixing up the number of syllables in each name for a more pleasing sound. In that school of thought, John Wayne D’Oh = bad (1 syllable each name, also serial killer middle name), Jonathan William D’Oh = good (3, 2, 1). Every member of my family has three two-syllable names and we haven’t found our lives hampered by them so I think you might be ok to break this rule if you wish 
My boy name list was:
James
Thomas
William
Alexander
Joshua
Without looking it up, those may actually be the top 5 boy’s names for the year… what can I say? I’m conventional. I had my grandfather and father’s names picked out as potential middle names - respectively, Douglas and Graeme (for you Americans, “Graeme” is pronounced the same as Graham and is exceedingly common in his age group over here).
I like a lot of the other suggestions I see here too… Christopher (I also like Christian if I ignore the obvious religious origin), Jeremy, Alistair, Jared, Walter.
I despise Jack. In my opinion, Jack is a nickname for John and not a name in it’s own right - the times, they may be a-changing but when I was younger “Jack” was my elderly neighbours, great uncles and other old men who were all named John on their birth certificates. These days Jack trendy and overused - you’ll recall that I haven’t let popularity dissuade me from the other names on my list but I just know so many Jacks that I’m heartily sick of it. Forgive me, anyone out there who has (or wants) a beloved Jack in their lives but it’s become a fingernails-on-the-blackboard name for me.
Arthur
Jason
Stephen
Robin
Rachel
Rosemary
Samantha
Wow - great suggestions. Thanks everyone. At work at the moment so unable to linger, but thanks everyone for sharing. Green Bean - ethnic background is WASP without the Protestant part I suppose. No religiosity one way or another.
Keep 'em coming!
M
I’m fond of Irish names for boys:
Cullen
Donnell/Donnelly
Dougal
Finn
No Aidans! Every boy in preschool nowadays is named Aidan!
Biblical:
Eben
Gabriel
Raphael
Noah
Solomon
Emanuel (don’t take this one, it’s mine ;))
Shadrach (okay, a bit out there, but sounds cool)
Greek and Roman:
Leander
Marcus
August
Dexter
I like longer names, so these should balance out nicely with a one syllable rhymes-with-O surname:
Benjamin
Timothy
Gregory
Nathaniel
Raymond
Sebastian
Jonathan
Zachary
Samuel
Atticus (We need more kids named Atticus.)
No no! Nobobdy should name their kid Arthur!!!
(I like being unique!)
Incidentally, my top choice for a girl was Rosemary, so good thinking, my brother in the produce aisle.
Mok’inathil’Aloraton’Icthylathonidras
Maxima-Optimus Destructicon
Ahem
Boy -
Isaac
Pier (I think that’s a name at least, and no, I most definitely do not mean Pierre)
Andrew
Jeremy
Frédéric
Girl -
Sakura
Zinah
Naomi
Shanna
Nina
Stacy
Zelda
Either -
Jesse
Sasha
Robin
ACK! ACK! NO! The one I am carrying now is an Abraham! You can’t have it! Slap Fight 
Oh. For the OP, Gareth.
Sidney
Gavin
Leonard
Scott
Kenneth
Rosemary…produce aisle…ah, I’ve got my suggestion: Sage.
Basil is another idea, but I prefer Sage.
No Stacy.
The world has enough of them. Trust me.
Stacy too dated, too ambisexual, too much of a last name and a boy’s name. No one will ever spell it correctly. This will make any daughter wish her name was really Anastacia.
Again trust me.
Naomi is much better. Pretty, historic and underused.
And just to add:
Sidney (English and French; Wide meadow)
Gavin (Welsh; White hawk of battle)
Leonard (Germanic; Strong as the lion)
Scott (English; Painted warrior)
Kenneth (Gaelic; Born of fire)