Entry clearance vignettes for UK visas have their validity marked with two dates "Valid from" and "Valid until". Are both of those dates inclusive? Or is the "Valid until" date the first date that the vignette will be expired from?
Examples of UK entry clearance vignettes can be found here, I am asking about the Type D vignettes at the bottom of the document, which are what are currently issued: https://www.gov.uk/government/publications/examples-of-uk-visa-vignettes
From a common English point-of-view, it is slightly ambiguous, but I would usually assume that both dates are included when listed and labelled as such. On the other hand, that would make the vignettes valid for a total of 31 or 91 days, when they are listed as 30 and 90 day vignettes. Using the example 30 day vignette in the link, including both dates gives 31 days total. This still makes sense if the first date is considered day 0, and each additional day is counted from there.
Would arriving on the "valid until" date still be acceptable?
Thank you very much!