Very varied speed test results - why?

[Stoofa]

Hi,

New here and sorry - couldn't work out the best sub-forum to post this one in.

So, I'm here in the UK and using an ISP called Talk Talk for my connection to the outside world. It's a fibre product offering "up to 80mb/20mb".

I've only been live for the past 10 days, but I've been keeping an eye on speed test results to make sure I'm getting what I'm paying for.

One of the sites I'm always being told to use in the UK is the BT Wholesale speed checker - this is located at http://speedtest.btwholesale.com/

Results have been all around the same since day 1 - around the 75mb/17mb range. This is what I'd expect and what I would regularly see when I was on a BT connection.

Another site seems to confirm this - http://www.broadband.co.uk/broadband-speed-test/

I did a check a couple of minutes ago and I'm getting a reported 75.3mb/17.1mb

 

So, I decided to use speed checkers that others recommend, so here at testmy.net and also at speedtest.net - this is where things are just not appearing right to me. My latest test here was reporting 11mb/16mb, the one before that 10mb/15mb.

Over at speedtest.net I initially got a 8mb/16mb result and that became 11mb/16mb after a few attempts.

 

So can anyone suggest why I'm seeing this wildly different set of results? How can I really test that I'm getting the kind of connection I expect and pay for?

Thanks for any help or suggestions.