Well done Emma. Those lambs grew well! Had they had much in the way of cake?
Carlisle mart's average was a smidge under £2 per kilo on Monday. Lambs over 42kg won't get as much as the average; VSS is right that the bulk of the market is wanting around 38kg liveweight (to give 20-21kg deadweight) and a really good, well-finished, double-muscled lamb at that sort of weight will get quite a bit above the average ppk.
It's all about horses and courses - if you feed a lot of cake, are short of grass / ground, or have other reasons for wanting a fast throughput, and are in it for the money, then you'd be mad not to have the type that will finish at 38kg and get them away as soon as they are at that sort of weight. (Assuming that type suits your ground and system.)
Suffolks are a heavier breed and not all suffolk crosses are fully fit at only 38kg - so they are often kept on to bigger weights, where they suit the butchers. (Our butcher wants them 45-52 kg for 25-28kg deadweight.) But the ppk won't be as high, there are less butchers lambs wanted than export / supermarket lambs.
But if you can fatten largely on grass, or with just a bit of cake, and don't need them away for any other reason, you may get as much or more per head for a heavier lamb at a lower ppk.