The Principal will invite the guest of honour to give the National Day message at 9 o'clock.
Is the guest of honour capitalised?
Learn English – Should “guest of honour” be capitalised
capitalizationnouns
Related Solutions
North as an adjective (and other cardinal points) is never capitalized, except when part of a construct that is capitalized in itself, such as a country name (North Korea, South Africa).
As a noun, it is capitalized when used in the game of bridge (North and South play together) and, more commonly, when designating a known part of a country (Virginia joined the North) or of the world (the mysterious East, the history of music in the West).
If you're talking about guests of honor in general, it definitely should be lowercase. However, as in your example, if you are talking about a specific guest of honor on a specific occasion, it could count as what Wikipedia calls a specific designator, so grammatically either way should be acceptable. However, looking at Ngrams to determine usage, it generally seems not to be capitalized.
Best Answer
Either "guest of honour" or "Guest of Honour" is appropriate. There is no universal rule for capitalizing the term. If you are publishing this phrase you should check your organization's style guide or past examples. Otherwise, choose which variation looks most pleasing in the specific context.