You guess.
They want to end prosperity and de-industrialize first world countries. Turn the whole world into something like Mexico, where the international capital can rule unrestricted by any local regulations. With a population that is brown, poor and submissive, with no real unity other than their desire to consume and their dependency on the global-corporate establishment, people who do anything for a job.
The end-goal is to reduce humans to an "abstract being", devoid of a culture, religion, beliefs, family , economic opportunities, and even a gender. Thus, they aim at leaving people with no identity (something that can put some resistance into people against their agenda), save for the depravity and consumerism they transmit through their mainstream cultural machine, or some global religion that reinforces good goy values and submission, like global catholicism (something in the lines of "Pope Francis") and Islam (Islamic men are extremely submissive and have hierarchy ingrained in them), preferably both competing with each other, to create more distress and disunity.
The main purpose of the mass third world immigration, perpetrated by globalist "world-government" proponents, is to reduce wages by increasing the labor force, and also to import more consumers to sell their goods to, since the people they bring in wouldn't consume as much in Africa and it wouldn't be that profitable. They want to make people dependent on state handouts (welfare), both natives and immigrants, forcing more people to compete for jobs in the weakening economies, in the service sector (as their slaves in china do all the manufactory and agriculture is controlled by big, GMO-based, global corporations), since they purposefully de-industrialize first world countries.
In these globalist-controlled service-based economies people have to beg for a job, to serve those in power. Only those educated enough, and that means programmed by their (((educational system))), who are well connected, and prove to be useful to them (by parroting the ideas they were taught in the educational system, to advance the agenda of those in power), get a place in society, and thus, to consume (enjoy access to a greater amount of consumer goods).
They want more "diversity" and to bring cultural and religious instability to former homogeneous nations, as this destroys national identity and allow the state to expand it's powers in the so called "fight against terorrism", terrorism that they actually support via CIA and MOSSAD, for example (and you just need to look at the Syrian Civil War, that they manufactured, and their carefully planned "refugee crisis", to see the proof of this).
England is one of the most advanced globalist-controlled police states out there. Good luck, user.