I'd like to know where the proposal to keep HSTs in heavy usage until 2035 came from! Certainly only a couple of years ago it was suggested that 2025 would be ridiculous, 2035 is outlandishly ridiculous. I see no way the HSTs, except for any preservation sets, will make it even close to 2035. Don't forget, that's another
21 years to go yet and the MTU'ing program/HST trailer program was only designed to give the HSTs a much needed 10 year life extension. That was concluded (with special exception to a few ex-EMT power cars now in use with East Coast - although I fail to remember the numbers at this time - and Grand Central's fleet by 2011) in mid-2008 on the Western, which it should be observed is now not far off 6 years ago (I know, that long already!

hock

. Some of the HST trailer sets and HST power cars were finished in 2007, so that lot will be 7 years into their 10 year life extension. I don't remember any being done in 2006, although it's worth remembering 43004 and 43009 were the prototypes for the MTU program, coming into daily use on the Western in either December 2004 or early 2005 (I honestly can't remember now, it's been way too long since my HST cranking days), so unless they've been touched up again since they'll be worn out sooner.
In previous HST discussions I've read on here (and let's face it, there's been a lot of them in the last 9 years, so my memory's getting hazy), corrosion on the HST trailers has been a major issue in the past. I don't remember what procedures were taken to fix this, but to suggest it won't be a contentious issue over the forthcoming years would be silly.
Just as silly is the proposed idea to use them on Glasgow Queen Street to Edinburgh services. Why would you do such a thing? 170s are more than capable of delivering most acceptable standards on an inter-urban route such as this one, quite I would imagine regular travellers may see shortened HSTs as a seriously backward step. It's also been mentioned about the work to extend platforms which would be neutralised if you have two non-passenger-carrying vehicles in the train!
So, I hear you ask, where would I use HSTs post-IEP? Well considering I don't see the prototype IEP getting started until
at least late 2015 now (so a little over 2 years late), testing wouldn't be completed if done properly for several months, let's call that all done and dusted by the end of 2016. Which, let's not forget, was the same year the IEP was originally to have been in squadron service by. Give it time to get Frothmas and New Year works out of the way, so we're into mid-January 2017. By this time electrifying the North West should be mostly complete so I'm not sending them there. TPX will be looking at a new fleet so sorry, no way will I be putting them on the Pennines. Hmm...
Well I'm not seeing any plans whatsoever to electrify much of Wales any time soon, same for the Western Region. The South East doesn't need HSTs, so with an ever so slight bias to Wales and the West, I'd use HSTs in a shorter formation (2+6 will do nicely, with options to extend them on match days in Cardiff) on services such as Manchester Piccadilly to Holyhead/Llandudno and Manchester Piccadilly to Cardiff/West Wales (I'm not specific on West Wales, my own plans for timetabling down that way would be significantly different to reality). I'd also utilise the fleet on services like Cardiff to Portsmouth Harbour and London Waterloo to Exeter St Davids/Paignton. I'd even utilise a few on peak services out of Birmingham New Street on the London Midland network. A couple of Birmingham New Street to Hereford services and a couple of Birmingham New Street to Shrewsbury services at least would be where I'd put them. Worth adding that I wouldn't be using them on every-lamppost-in-sight peak time workings, good golly gosh no, I'd use them on proper workings!
That's what comes to mind at silly o'clock in the morning at least. I can't be bothered to consider details like First Class provision. Finally, I'd like to point out I'd like to see the HST fleet carry on for as long as possible but there are limits to everything!