Re: No issues visiting India
Vietnam: Walk through customs, after being told by airlines that I had no visa and would be refused. Checked at airport with custom, are you from England? Yep. Big smile, welcome to Vietnam you have 15 days. Visa for 3 month renewed by sitting in a coffee shop and sending someone to do it for me.
I will say a British passport is quite handy, along with it being a G8 country, especially to poorer countries, they don't really expect you to be trying to smuggle yourself in as an illegal immigrant (in fact it's often come here spend money), and British terrorism has gone down since the Empire.
Never had any trouble at any border in Asia, and that includes standing with a gentle sway, very bleary eyed at a Malaysian border after a rather heavy night drinking and valium (I was young and stupid), with a big sign saying 'Drug smugglers Will be killed' note killed not shot.