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Someone wiser than me once said "there are no stupid questions, just stupid answers"
The connection icon in your toolbar is measuring the connection between your network card (in your computer) and the cable modem or Set top box. These typically are set at 10 mbps, so you've gained a bit. You might be using a wireless connection, typically rated at around 11mbps.
The service speed will have changed but is only apparent at the modem / Set top Box into ntl's network. The maximum speeds of the broadband service will always be less than your network connectors between your PC and the modem/STB.