Why is England so expensive?

I'm 14 and around December my mum bought me vans (the old school ones) for £55 which is pretty expensive ($91.45!) but in america if they're $55 that's only £33.08
So whys it so expensive?
All clothes and everything are really expensive too. If you go to topshop jeans are like £36 which is $59.86!
Most of my clothes are pretty expensive but if you convert them into dollars most of them go above $100 and I'm not a person who spends £50 on every top I buy.
For my birthday I got beats mixrs and they're about £190 and in dollars that's $315.93!
Why is it so expensive! I'm not spoiled
This applies to everything not just clothing and electronics.
I go to a private school not everyone here does by the way and its really expensive for a year it's £10000 ($16628!) So how is it so much higher in dollars?
Iphones seem to be really common in both countries (most people here have them) and the iphone 5s goes from £549 (to higher depending on data)! That's $912! In america assuming they're $500 that's only £300!

So why is it So much more expensive here? I'm sure a lot of people will be shocked actually
My parents wouldn't get me an iphone if I wanted one like most people's would (I don't want one) but I do have an htc one which is the same price (paid for it myself)

Thanks!

Added (1). @Matthew I didn't mean to come off as spoiled! I'm not saying I want an iPhone I'm just stating how much they're worth. Also I paid for my own phone which is pretty rare for my age. I would be fine with my old phone (a blackberry which I also paid for) but it broke

Almost all are expensive these days because of population…

England is not especially expensive… LONDON is.
But the rest of the country is not really more expensive like
other first world european countries,
(In general "western" europe is a little bit more expensive than the US anyway.)

I agree with fear

The pound is worth more than the dollar that's why it's more expensive, infact £1 is worth about $1.50 and shipping costs, tax and phone companies differ

Also no offense but your parents are paying £10,000 for you to go to school and you want a £500 aswell, that is pretty spoiled. I had a £50 slide phone and went to a public school, just be grateful for what you already have.

It is what they can get by with. A product becomes popular, and the price is jacked up. I remember when Vans were $5, about 2.5 UK

Depends on currency trade values

It's what they can get away with charging, and still have people willing to buy. There are many complex reasons for this, but that is the bottom line.

You might be interested to know that, in the motor industry, they have referred to the UK as "Treasure Island" for decades. This is because they have always been able to get away with selling cars in the UK for MUCH more than they can sell them in other countries. Brits have been seen as "mug punters" by many industries for a long time.