If you place a £1 bet at a high street bookie at 6/1 you would receive £7 in return, the same as online. I suspect that the confusion has arisen over the decimal odds system, 6/1 is the same as 7.0
Therefore a bet of £1 at 7.0 returns £7 (Not £8).
"All you need to ask yourself is do you feel lucky? Well do you......Punk!"