Apologies; my reference to services being subject to 'States agreement' was to air route licensing. The reference to 'timetabled' services suggests a mix of ad hoc and scheduled flying. 2-REG
guidelines indicate that the States now award AOCs to public transport operators (I haven't looked very hard but can't find reference to any specific limitations on single engine IFR over-water ops.) Given political and popular pressure, CICRA scepticism and the competition situation, likely that a GCI-JER application would be approved; could see this succeeding against SI/BE's more infrequent (and possibly higher cost?) operation against a strong backbone of air taxi work. Likewise for thinner, seasonal, CI-UK routes currently unserved. Any attempt to gain a foothold on more established routes would be likely to fall foul of the Board, subject to the representations it received.
(Recent licensing history for those less familiar: after purchase of BE slots at LGW, and hearing of the likelihood of rejection upon further enquiry, U2 did not bother to apply for GCI-LGW. SI withdrew from a GCI-BRS application prior to a hearing, and the Board only approved BE's GCI-LTN application on the basis of stringent year-round operating conditions. Its composition changed substantially after the 2016 election, to include a number of populist and pro-business members. It has not been called upon to decide on contested applications since then; its likely position on proposals for competition with existing operators is thus unknown.)