"It is incumbent on the current government to honour the pledge of its predecessor."
Actually, no it's not, and indeed one of the cornerstones of any democracy is that the government of today cannot be bound by the government of yesterday. This is why laws can always be repealed, or amended, or superseded; it is why new laws can be brought in, why treaties can be withdrawn from.
And it's why a second referendum is absolutely not undemocratic. How can it be? You've just asked the people again. The UK of 2016 has gone -- sometimes literally, given that over the last two years, some voters in 2016 have died, and others that couldn't vote then now can.
The real anti-democracy, then, is those that wish to pretend that the 2016 decision is absolutely final, and absolutely must be respected come what may. Nonsense.