I was there at the beginning, and thankfully fastened my seatbelt. I hate fairground rides – the screaming, the nausea, the dramatic music before you’re hurled gung-ho with gravity-defying neglect for your nerves and muscles. Living as a string quartet ‘other’ violinist is the proverbial roller coaster, yet I can’t get enough.

I’ve seen a few ‘Castalians’ come and go since the group was formed in 2011, all of them having a profound and treasured impact on that mysterious energy that exists somewhere between the four seats, each new member upping the voltage. We could gather a Mendelssohn Octet, though I think we might blow a fuse.

Charlotte has been sat in the next chair through most of it, a refined firecracker of a petite soeur who frequently overdoses on chocolate and is only just above the ride’s height restriction. We’re not related – our publicity shots negate the need for DNA testing – but there’s a mutually reliant rapport that borders on the Siamese. Both of us have fleetingly dallied with the idea of shimmying over to the first violin position in its vacant moments, but the operation would be far too painful. After much soul-searching, we realised we’re conjoined for life (Charlotte on my left!).

Chris came next, with merry circumstance and infinite pomp. We’d met some years back at the Royal College when he’d taken pity on a poor Welshman getting to grips with London life and a rare foray up the E-string as first violin in Korngold’s Sextet. He subsequently hot-footed it to the salubrious serenity of Lugano and returned just in time to take my call: ‘Chris, we need you’. If Charlotte and I are siblings, us boys are a double act hellbent on entertaining ourselves with close-to-the-bone wisecracks and godawful accents.

Sini’s quartet birth was the result of an international email exchange that ended up in my bathroom via our mentor’s Berlin bedroom. It wasn’t the first we’d heard of her. No, she’d held us spellbound – like the Christmas toy in Hamley’s it’s-the-season window display that was out of your parents’ budget – at a festival in northern Germany the previous year.

In the meantime, we’d begun a CIA-style hunt for a new first, vetting and vetoing a long-list of ferociously gifted fiddlers. This can be both a painful and rewarding process, often more a test of the existing three quarters than the candidates themselves. There are bound to be disagreements along the way, and it’s surprising that three musicians who adore playing with each others can have such opposing views on a fourth’s qualities. However, when all had been digested, the lower three ensemble echelons (I speak only of pitch, of course – I mean, who’s to say second is second, or any worse than first, just because I’m buried in the middle, melody-less but for some moments that take even me by surprise….I could have been first, so my Mum says, and my shrink agrees, it’s a lifestyle choice, like playing goalkeeper or marrying an insurance salesman) had become almost impenetrably intertwined – not necessarily a good thing for a potential ‘leader’.

The fabled email came through in February 2014. Sini had a burning desire to join a string quartet, and had foolishly reached for her computer instead of a hosepipe. In we swept, stoking the embers as rapidly as my fingers could type a reply. And here we are: ‘her string quartet from London’, she frequently announces between philosophical musings and zoological fantasies.

Then there’s me. When I was young I made the mistake of taking ‘you’d make a good second violinist’ as a compliment, and off I went, timing my ‘cha chas’ with worrying satisfaction to the main ‘oom’ beats as the first violinist took all the glory, but the same pay cheque. I’ve been lucky enough to have had some great teachers, but nothing could have been more educational than immersing myself in a master musician merry-go-round. I’m buckling this current crop of Castalians firmly into their seats – I’m done with being dizzy.