alt Hacker NewsWhat? No that will not allow you to buy "most houses in London in cash after saving for 5 years" unless you live far out of town in a tiny place and eat plain rice for 5 years, and even then it'll be long odds.
First, you'll take home slightly over half of that net of various taxes and deductions, but let's be generous and say your take-home is 200k. You live very frugally, don't go out, don't really buy anything and keep your costs at 50k a year, including rent (!). That leaves you with 150k a year, so after 5 years you have 750k. This allows you to buy a modest 2-3 bed row house with a postage stamp sized garden in one of the less desirable areas of the city.
If you want something that doesn't look like a shed, you are looking at 1 million pounds and up, more like 1.5 million. If you want in a nice area and large garden, make it 2 million.
What are you smoking? The median house price in London is 500k. At 750k you can afford 77% of houses and at a million you are in the top 10%. 50k per year is also a preposterously high expenditure. Rent will be your leading expense by probably a factor of 10. You could put aside 3k a month for rent (again, totally preposterous number) and not touch the sides.
The only thing I can think of that would even come close to making a difference is having children. Then all bets are off, they can cost as much as you like.