I think I better use my personal account:p
Maybe you can say Frontier is the basic suiting collection of Harrisons. Non super, no cashmere blend. It has a bit rough surface so you won't expect "luxury" feeling. It emphasizes more on performance and breathability. Moreover, it has >90 patterns so it is a good choice for building up your wardrobe.
The same with other Harrisons collections, Frontier is made in the UK. I have just received my own navy windowpane Frontier suit, which I like it much.
Actually there are many 100% wool suiting collections just slightly more expensive. For example, Fine Classics, which is a 12oz worsted suiting fabrics with many traditional patterns. Let me show you later.
Do you have a suit made-up using Harrison Fine Classic?