Excess fares via London

[NigelH]

I've seen lots of helpful information here on paying excess fares to use a ticket via a different route, but I have a question that I haven'rt seen covered. If I'm travelling from Reading to any station in the North (for example Kendal), then two off-peak return tickets are offered: a cheaper one via Banbury and a more expensive one via London (or in some cases via any permitted route). If I buy the cheaper one and then want to return via London, I understand that I can buy an excess for half the price difference to allow this, but will that excess ticket then let me through the barriers to use the underground between Paddington and Euston, since the "via London" route that I'd be upgrading to includes the underground?

 

[Bletchleyite]

If you excess it to route +LONDON then yes, the excess should let you through the barriers. Pretty sure I have done this.

 

[Hadders]

I agree with @Bletchleyite , in my experience the excess coupon will operate the underground ticket barriers. Note that it is common practice to staple the excess coupon to the original coupon which can cause issues in which case just ask the staff to let you through manually.