You are quite right; I missed that, sorry.

Then the position is clear: The OP cannot travel to the UK on the basis of his wife's ancestry unless she travels with him.

Therefore, it's equally clear that he is trying to sneak in illegally. It's his wife who has an ancestry visa, not him. He only has a visa as a dependent of his wife's.

My understanding is that a person living in the UK on the basis of being a spouse/partner of a holder of a UK Ancestry Visa is entitled to work. (Note, though, that the granting of the visa in the first place – to the main visa holder – is dependent either on that person intending to seek and take employment, or on that person having a job to go to.)

I am not sure, however, of the need to travel with the main visa holder. Certainly that is not the case once everyone has arrived (i.e. the spouse can travel abroad and return to the UK without the need for the main visa holder being present with him or her on the trip). This may be true as well for the first entry – I don't know – but if it is there might be need for proof to be shown that the main visa holder will be travelling to the UK forthwith. Certainly the subsidiary visa holders can enter for the first time after the holder of the main visa (which is a very different thing, of course). The best way for the OP to clarify this would be to check with the British High Commission in South Africa, or to seek the advice of a competent lawyer who knows about British immigration matters (and there must be some in South Africa). What does the visa in your passport actually say?

Also to the OP: there is no point in trying to "sneak" into the UK via Ireland or via some regional British airport. If you have the right to do what you propose to do – which you need to clarify one way or the other – then there is no need to. If you do not have that right, then the Irish will be on to it (they, after all, will see the visa in your passport, and moreover they are very alert now to people trying to use Ireland as a "convenient" way to enter the UK), as will the immigration officers at any British airport.

Good luck with finding out what you need to.

I think that in relation to first entry, the spouse must either accompany the principal visa holder or travel after the principal visa holder has already been admitted to the UK. This is because of paragraph 194(i) of the Immigration Rules, which requires that "the applicant is married to or a civil partner of a person with limited leave to enter in the United Kingdom under paragraphs 128-193". As the principal visa holder will not have leave to enter until they arrive in the UK and are admitted, it follows that the spouse cannot travel to the UK before the principal visa holder if they wish to be admitted in this category.

Good point. That would have been the case, certainly, but now a visa is taken as granting leave to enter, which is confirmed (rather than granted) by the immigration officer at the port of entry – and of course entry can be denied at the port of entry, thereby in effect cancelling the leave. (This change was introduced partly as a time-saving device to try to avoid the routine need for long immigration interviews at airports; whether it has succeeded in achieving that aim must be doubtful, but that's a different point.)

Whether, however, this definition of "leave to enter" is accepted in terms of the entry of a spouse or partner of the visa holder, I don't know. It may well not be – but as just about everyone has said, the OP needs to find this out before his departure for the UK, rather than just hoping for the best or trying to sneak in through Ireland or a minor British airport!

But Article 4(2) of the Immigration (Leave to Enter and Remain) Order 2000 says:-As I read it, that means that the visa does not operate as leave to enter until the visa holder arrives in the UK. At that point (but not before), they are treated as if they had been granted LTE before arrival. Or, in other words, these provisions do not mean that the visa holder already has LTE before they arrive in the UK.

Usual disclaimers about all this: Just personal musings, does not constitute formal advice, do not rely on my pre-coffee ramblings.

No, but your musings sound good, even pre-coffee. And I think you're right. If so, it would mean that the OP cannot enter the UK, as the holder of the spousal visa, in advance of his wife, the principal visa holder. And that certainly makes intuitive sense, I suppose.

In any case, the OP appears to have left us...

Simple answer here from experience of having to refer a similar case to UKBA.

Any derivative status for a dependent or family member is conditional upon the maintenance of the status by the principal status holder. The derivative status is not actually considered to be held until the principal status holder actually holds the status.

Of course, there may be subtleties in your case that are different but the interpretation by UKBA is likely to be consistent.