GOG.L Share News (GOG)

(ShareCast News) - Commuters on Britain's largest railway franchise were lumped with the promise of more misery this week, as conductors on the Southern arm of Govia Thameslink Railway announced a strike, set down for next Tuesday.The railway franchise - a joint venture between FTSE 250 firm Go-Ahead and Keolis - currently sees hundreds of trains cancelled daily, averaging five times as many cancellations as the second-worst performing operator.Conductors lie at the heart of the issue, which began when the first strike in the dispute was called on 26 April.According to figures supplied by GTR, an average of 23 conductors were off sick each day since then - the figure has now risen to an average of 40 conductors calling in ill each morning.The row began when the company announced it wanted to have drivers close train doors, rather than conductors - turning conductors into a more customer service-focused role.But the Rail and Maritime Transport Union has said that would lead down the slippery slope to driver-only operation, which it claims would create a serious safety risk to passengers.Some of Southern's suburban London services are already driver-only operation, however, and have been for 20 years.Rail Minister Claire Perry waded into the debate this week, telling the BBC the clear increase in conductor sickness is effectively a "work to rule," and is "outrageous and unfair".But the union has rubbished her rhetoric, saying it has examples of trains being cancelled even when staff are available.Earlier this week, Go-Ahead issued a profit warning amid the GTR chaos, slashing its margin forecast for the seven-year life of the franchise to 1.5% from 3%.That led to a nosedive for its shares - they were last down 3.87% on Thursday.