Not to fuel a constantly pointless debate but:
(1) HYPSM are not more prestigious than Caltech. Neither is Caltech more selective than HYPSM. There is no evidence for any of these two statements. Caltech's though is highly selective and Luthervan is correct that they have a higher enrollment yield than Harvard, Yale and similar schools. This is because they are highly specialized. If you apply to Caltech you plan to study a quantitative subject and only MIT, Stanford, Harvard and maybe Princeton are comparable. Very few students will turn down an offer from Caltech. There are lot of schools that US students will turn down for Harvard, no one in their right mind will consider turning down LSE for king's college london or Warwick, not to talk of Oxford.
(2) Endowment is an American phenomena. I think British media and academia are misinterpreting or appropriating the success of American Universities to money. As a result there has been a recent rush to increase university endowments under the guise that it would make British universities world on the international scene. Nevertheless with respect to UK domestic reputation, endowment does not mean much.
(3) Warwick is undoubtedly more prestigious than KCL. Top and Global Employers tend to target Warwick. IB and Management consulting firms hold Warwick in higher regard. Most don't visit King's College London.
Notice that Luthervan skillfully deflected the question of "what career fields does KCL beat Warwick " instead sidetracking it to one regarding the list of alumni. (With dripping sarcasm) Yes, the number of Bishops that KCL has produced will have a significant impact on student employment since the large majority of top students dream of heading into the clergy. Infact by virtue of going to KCL you are guaranteed to be a Prince or President or TV personality.
There is really no prestigious graduate scheme that considers KCL significantly over any other school which is what Roxas posed as a question. Its not well-known for engineering (and in the spirit of fairness neither is warwick) so it is not targeted by engineering employers. Most students are looking for employment, not superficial metrics such as how many students in the long-term end up as entertainers.
(4) In the OP's case KCL is the better choice due to its location. Now if your goal was a job at say Goldman Sachs or Mckinsey, Warwick would have been the better option. However, you would have no problem gaining employment at an international thinktank in london, if you wanted to do war studies, which is by the way not the top IR course in the UK not to talk of the world. That claim goes to Oxford and LSE. KCL is the only school that offers the War Studies Course.
(5) Except you are from Asia, and can speak Mandarin, Japanese or any of the prerequisite languages required to work in an asian country, as well as possess work authorization, you should be less concerned about the prestige of your university in that country. Most British students will be working in their home country, and at best in anglophone countries.