Ok first for info only what is ' ECO ' ?.
Entry clearance Officer.
Second, accepting the proposition that she must apply from outside the United Kingdom, which Rule specifies that this non-UK country must be her 'home' country or one in which she 'resides' ?
How did she obtain entry clearance for her student visa? From where did she obtain it? My presumption is that this was obtained in her home country because she is legally resident there? Okay, if she obtained it from say France, she must have been legally resident there in one category visa or the other I would presume.
To directly answer your question, there is no rule written in black ink. You might be willing to take up a legal challenge and argue this with the secretary of state if you so wish but I personally don't think it would take you far.
And if the latter - what and where is the definition of 'resides' ? Ie, if she takes a trip using a Schengen visa from the UK to France she will be - for the duration of the trip - 'residing' in France, n'est-ce pas ?
Thank goodness for google, you'll be amazed at fountain of infomation out there. It's just a click away.
Resident in the UK means (i think) - not having immigration restriction to your length of stay. An ILR holder or a British resident for example. Being in possession of a schengen visa does not count as there is a limit to your length of stay. So that wouldn't qualify.
By the way, I don't follow the logic that only applications from outside the UK avoid the sin of queue - jumping ? Surely the 'queue' consists of a pile of applications in one or more In-Trays in the relevant department of the Home Office, and whether those applications arrive at the bottom of that In-Tray from an UK Embassy abroad, or from a Post Office in Much-Immigrating-in-the-Marsh doesn't seem to me to affect where in the queue it is .
Misplaced argument. I would rather take that up with the AIT or the UKBA. Chikwamba case law does seem to agree with you to an extent, though.
Personally, I think it's queue jumping when an illegal immigrant with no compassionate circumstance would rather twist the arm of the home office to grant them leave to stay(My own personal opinion).
Now, if the home office clearly states in it's rule that you will not meet the requirement of a category if you are not in possession of either a spousal visa or an unmarried partner's visa - I think they have set their parameters. It is now your prerogative if you would rather fight them to say they are unfair. It is queue jumping if you already know the rules but trying to circumvent it.
Going to Timbuktu on Schengen visa would not help you. It's just so cut and dry. Follow the rules and you have a better leverage for argument in court.
But - once in the queue - how long roughly do the applications take to progress ?
Legal queue - ie returning to home country to apply for entry clearance, you mean? If so, there is a service level agreement of 21 days. I personally would estimate 4 weeks.
In country applications ie. 248 should be around 4 weeks too but don't quote me on that.