new fibre install

[#1]

I have just had my fibre optic installed I was told by the engineer I am getting about 40 megs when he plugged his machine in the wall ,but now both modems are connected its only about 12 meg ? my broadband has been running for about 1 hour ,will my speed gradually increase of the next 10 days , my modem is in the hallway and my wireless adapter in my pc the other end of the house is showing only 1 bar but surely this cant be the reason?  I am from Monmouth and the green box is about 600 yds away .
 

[#2]

http://www.speedtest.net/my-result/3659552667

[#3]

It can indeed
If you do the BT speedtest then Further diagnostics what does it say http://speedtest.btwholesale.com/
Also what is the current line speed from https://portal.plus.net/my.html?action=data_transfer_speed

[#4]

Could you also try connecting via Ethernet at all to see how the speeds compare?