So, throughout the years I’ve seen a lot of Thorn products. I’m sure we’re all familiar with the famous Beta 5s, the underrated Beta 3s, and apparently there was a Beta 4 at some point.

My question is: what the heck does “Beta” mean, and what’s up with the numbers? There’s 3, 5, 49, over 9,000… what do they represent?

I think it all went Alpha, Beta, Gamma when it all changed from Atlas to Thorn, and it was in ascending order on most things, their was a Beta 1,2,3,4,5,6….and so on, but some numbers dropped out when lantern models went obsolete over the years.

Thorn is a UK company. Our roads can generally be classed into A roads (major), B roads (minor), or M roads (motorways).
The Alpha series was intended for major roads (A for Alpha), the Beta series for minor roads (B for Beta), and Gamma for general illumination (G for Gamma). Alpha saw use on motorways, too.
As far as I'm aware, all the numbers are just model numbers.

It's a similar system with Philips UK lanterns. MA50, MI26, etc. MA - Major, ME - Medium, MI - Minor, MO - Motorway, MU - Municipal.
ME, MO and MU were uncommon, though with MI and MA filling most roles.

That makes perfect sense, thank you. 

Thanks guys for the info! The mystery has been solved, at least for the clueless US members such as me.

Not just the US members... 

I didn't know what the difference was.!

Oops, how embarrassing. Gemma must feel ashamed.

Well she does go a bit pink when she comes on... 

AngryHorse - I believe most of it was name changed from AEI to Atlas. The AEI Beeby (Beta 1), AEI Amber Minor (Beta 5), AEI Saxby (Beta 6), AEI Optisec One (Alpha 3), AEI Junior Amberline (Beta 8 ), AEI Ashby (Gamma 8 ), to name a few. Atlas carried many of the A B G names, and Thorn continued the legacy.

Econolite03 - My pleasure

Mandolin Girl - While I wouldn't recommend road & street light classifications for a speech, it's nice trivia . 

Interesting, was it that early?, the Alpha/Beta thing makes sense with the roads though, I hadn’t thought of that! 

Indeed. Mike Barford's collection as some Atlas Alphas and Gammas in it, along with many Thorns.