Penzance to Fort William, Oban, Wick, Thurso & Kyle of Lochalsh, using 5x2 car 158s, refitted to be 1+1 throughout, with buffet in the Wick portion of the train, trolley service provided on other portions upon dividing (excluding Thurso).
From Penzance, this train will call at St Erth, Truro, Par, Bodmin Parkway, Liskeard, St Budeaux Ferry Road, Plymouth, Totnes, Newton Abbot, Teignmouth, Exeter St Davids, Taunton, Weston-Super-Mare, Bristol Temple Meads Bath Spa, Westbury, Salisbury, Romsey, Southampton Central, St Denys, Swanwick, Fareham, Portchester, Cosham, Havant, Chichester, Barnham, Ford, Worthing, Shoreham-on-Sea, Hove, Burgess Hill, Haywards Heath, Gatwick Airport, Redhill, East Croydon, Norwood Junction, Beckenham Junction, Bromley South, St Mary Cray, Swanley, Otford, Bat and Ball, Sevenoaks, Tonbridge, Paddock Wood, Headcorn, Ashford International, Folkestone Central, Dover Priory, Deal, Sandwich, Ramsgate, Margate, Faversham, Sittingbourne, Rainham (Kent), Gillingham (Kent), Chatham, Rochester, Strood, Gravesend, Dartford, Slade Green, Abbey Wood, Woolwich Arsenal, Charlton, Blackheath, Lewisham, London Bridge, London Blackfriars, City Thameslink, Farringdon, London St Pancras, Kentish Town, West Hampstead Thameslink, St Albans City, Luton Airport Parkway, Luton, Bedford, Wellingborough, Kettering, Corby, Oakham, Melton Mowbray, Leicester, South Wigston, Narborough, Hinckley, Nuneaton, Coleshill Parkway, Water Orton, Birmingham New Street, Smethwick Galton Bridge, Sandwell and Dudley, Wolverhampton, Telford Central, Wellington, Shrewsbury, Whitchurch Shropshire, Nantwich, Crewe, Alderley Edge, Wilmslow, Heald Green, East Didsbury, Manchester Piccadilly, Manchester Oxford Road, Deansgate, Salford Crescent, Bolton, Horwich Parkway, Chorley, Leyland, Preston, Lancaster, Carnforth, Arnside, Grange-over-Sands, Ulverston, Dalton, Barrow-in-Furness, Ravenglass for Eskdale, Sellafield, Whitehaven, Workington, Maryport, Carlisle, Lockerbie, Carstairs to Motherwell, where the train divides. The front Four coaches continue to Fort William and Oban, calling at Bellshill, Argyle Street, Glasgow Central, Partick, Hyndland, Anniesland, Westerton, Dalmuir, Dumbarton Central, Dalreoch, Cardross, Helensburgh Upper, Garelochhead, Arrochar and Tarbet, Ardlui and Crianlarich, where the train divides again. The front two coaches continue to Fort William, calling at Upper Tyndrum, Bridge of Orchy, Rannoch, Corrour, Tulloch, Roy Bridge, Spean Bridge and Fort William. Coaches 3 and 4 of this service continue to Oban, calling at Tyndrum Lower, Dalmally, Loch Awe, Falls of Cruachan, Taynuilt, Connel Ferry and Oban. The rear six coaches of the train are for Wick, Thurso and Kyle of Lochalsh, and from Motherwell will call at Whifflet, Coatbridge Central, Greenfaulds, Cumbernauld, Camelon, Falkirk Grahamston, Polmont, Linlithgow, Dalmeny and Inverkeithing, where this train will divide again. Coaches 5, 6, 7 and 8 of this train continue to Wick and Thurso, calling at Dunfermline Town, Dunfermline Queen Margaret, Cowdenbeath, Glenrothes With Thornton, Markinch, Ladybank, Perth, Pitlochry, Blair Atholl, Newtonmore, Aviemore, Beauly, Dingwall, Alness, Invergordon, Fearn, Tain, Ardgay, Culrain, Invershin, Lairg, Rogart, Golspie, Dunrobin Castle, Brora, Helmsdale, Kildonan, Kinbrace, Forsinard, Altnabreac, Scotscalder and Georgemas Junction, where the train will divide again. Coaches 5 and 6 continue to Wick only. Coaches 7 and 8 continue to Thurso only. The rear two coaches of this train are for Kyle of Lochalsh, and from Inverkeithing, this portion of the train will continue to Kirkcaldy, Markinch, Ladybank, Cupar, Leuchars, Dundee, Arbroath, Montrose, Laurencekirk, Stonehaven, Aberdeen, Dyce, Inverurie, Elgin, Forres, Nairn, Muir of Ord, Dingwall, Garve, Lochluichart, Achanalt, Achnasheen, Achnashellach, Strathcarron, Attadale, Stromeferry, Duncraig, Plockton, Duirnish and Kyle of Lochalsh.
But if this did end up becoming a real service, I would hate to have the job of annoucing at Penzance (assuming that it isnt already automated)