If a train is booked to go via High Wycombe, then of course a Route: via High Wycombe ticket is valid! This has been checked and clarified with both Virgin Trains and ATOC.
I know a few people who had problems with staff at Euston a few months ago. There is/was a known issue at Euston regarding ticket acceptance
generally that was identified by members of this forum a while back, and I am very pleased to see that Virgin have done - and are continuing to do - a lot of work to address those issues.

Someone wrote to Virgin about this issue and got an apology and assurances that steps would be taken to train staff. Given that no issues have been reported recently, it looks like the message has got through.
There will always be a small minority of staff who do not read their notices and incorrectly charge customers. For example, there is one notoriously well-known guard on East Coast (
not based in Yorkshire, Scotland or London) who appears to have no desire to read ECs PTUs, nor the Routeing Guide, NRCoC or The Manual. He issued a UFN to a member of this forum in August 2010, the details of which I will not go into, and this was quashed. He continues to cause trouble. The same is true at most TOCs with one or two rogue individuals causing bother. If a guard acts incorrectly, you will be able to get an apology and the fare refunded (or UFN cancelled, as appropriate) and there are members of this forum (including myself) who are happy to assist with proof reading any letters. Customer Services are usually happy to receive such reports, as the rogue individuals are often known about but they're powerless to do anything about them unless customers complain. Any letter of complaint should be concise, polite, but assertive.
I wouldn't have any concerns using these perfectly valid tickets; though I would book online and obtain a reservation if possible (this is evidence of a contract). If a guard does not accept the ticket, then gather evidence for your letter of complaint. If the ticket was not valid then the correct action would be a change of route excess to the appropriate fare charged at HALF the difference between the Rte High Wycombe fare and Rte Any Permitted fare (with Railcard discounts, if the original ticket was discounted). In this case, the excess would be £9.30 (fare paid: £25.00. Appropriate fare: £43.60. Difference: £18.60. One portion: £9.30) If they charge new ticket, then not only are they incorrectly refusing a valid ticket but also not adhering to procedures. That makes it more serious (for them). I would comply with their request to pay, but state that as you fully expected the ticket to be valid, you have no spare money with which to pay immediately, and in any case you will be appealing. Do
not ask for a UFN as this is not a good idea. You should be issued with a UFN, this can easily be cancelled. I am happy to assist anyone in this situation. Be polite, compliant, and gather evidence.
But, chances are, there will be no problems using these tickets
