Jack is right - the Original Low actually has two gradings and the one we were referring to is the grade 1 one, which is £200 RRP and the G2 is £150 RRP. The Solution is also available in 2 gradings, the grade 1 is £300 RRP and the grade 2 is £250 RRP.
It's quite strange when you think the G1 Original Low costs a lot less than the G2 Solutions, especially as they're exactly the same shape!
Basically M&H prefer the cosmetics on the Solution a lot more, and that's the only difference they revealed to me. To be fair, even the Grade 1 Original Lows have blemishes, but apparently the same can't really be said for the Solution. How this warrants a £100 difference in cost, though, I'll never know, and that's why we only stock the Original Low!