I think the 21 age rule sounds faily sensible.
When my wife took her ilets in manila her desk mate was taking the exam for 2nd time to get a certain level so he could go to aus as i think both aus and canada both require a certain level of english before entry.
I think the 1000 pound bond would have to be higher if you were desperate to bring in one member of family some might think it worth it.
Im surprised it wasn't a high rate of income tax or some other tax as its labour.
The confidental interview may have uses in certain countries and cultures i guess.
