I'll just join in and say that I too have a medal to a man in the 8th Foot (King's Liverpool Regiment), with clasp for Peiwar Kotal.
The 8th Foot were part of Roberts' Kuram Valley column (apart from two Companies who stayed at Thal and Kohat as part of the garrisons there - Mark, maybe your Lance Corporal was with those). They were involved in the battle of Peiwar Kotal - as part of the smaller frontal attack, rather than Roberts' main turning movement via the Spingawi Kotal, but it was still severe fighting. The regiment spent the rest of the first campaign at and around the base camp at Peiwar, with the occasional tribal pressure to deal with.
It wasn't until the commencement of the second campaign, renewed by the murder of Cagavnari at Kabul, that the Thal Companies rejoined the rest of the regiment, still at Peiwar. They did not advance to Kabul with Roberts, but stayed in the Kuram, doing regular day-to-day field work, at one point in October 1879 having to help repel an attack of Mangals and Jagis at Ali Khel. Forty men took part in the Zaimusht expedition in December, and the attack on Zawo, and there were other expeditions in 1880 to Bannu and Karmanna. They returned to India in Oct 1880.