BT Wholesale - speed test

[#1]

How reliable is the above test for broadband speed?
my router shows downstream connection speed at 2.5mbps has been for months.
Yet BT shows everything between 0.2mbps and 1.7 mbps with occasional speed of 40.00 mbps 

[#2]

You could compare to an HTML5 based speed test link below:
http://www.broadband.co.uk/broadband-speed-test/

[#3]

In my experience I've found HTML5 based speedtesters to give more "variable" results. They seem to be far more sensitive to which browser and OS and your processing power.
I've generally found that the BTw test gives a good indication of the capability of the connection, but do test at off-peak times as well, and make sure nothing is using the connection apart from the test.
Compare with this TBB x1 & x6 test. Again do a test at off-peak times.
Never rely on just the results of one test.
Downloading Test files from TBB will give a better real world idea and nor rely on Flash/Java/HTML5.
If everything is running as it should be, you should gets speeds very close to the BT IP Profile, but things will usually vary at peak times.