In my view 21.Qg5 was deadly., threatening 22.h5, and there was not a whole lot Black could do about it.

The rook can not hold back the White h-pawn. I think I would have preferred ...Kf8, here.

Agreed. The pawn could not be stopped anyhow, so the rook might as well have stayed on the g-file.

Black has to try some kind of counter-attack. This is one of those situation in which the 'best' move is no help, but a second-best or third-best move might offer an opponent some attractive way of going wrong, or at least introduce nebulous complications.

23.dxc5 Qxc5?? 24.Nd7. Or 23...Qc7 24.Rd1. Hard to fathom why this pawn advance got the nod.

Time to bring in the inactive rook. It is doing diddly squat on a1.

One forms the notion that White may be mixing plans. He has thought of at least two ways to proceed, but is tangling them together. Very, very easy to do when one has much the better position, but no immediate forcing line available.

Neither side seems willing to break the tension at d4-c5. But it was to the advantage of whoever did so. Even Black, though it would not have equalised the game, would at any time these last few moves, have benefited from ...cxd4.

After 26...cxd4 27.cxd4 Rc8, Black would have at least the potential for counter-play.

Good enough. So was 27.dxc5.

Forced.

28.Rxg4 with 28.Rhg3 to come, and a massacre on g6.

29.Rhg3 - stacks on the mill at g6 - would have been winning. Black has been offered a fleeting chance to get back into the game. White MUST have overlooked something, here: 29.Qd7? Be6! 30.Qxd6 exd6 31.Nxg6 ... (forced) 31...Re8 32.Rhg3 cxd4 and Black might just fancy his chances to hold. Black's threat of ...Bf5 leaves the knight on g6 looking a little sheepish...

Sometimes you have to bite the bullet, That is one of the weapons available to the side materially ahead: to threaten exchanges to force the opponent into a passive position. Sometimes the defender simply has to accept exchanges to avoid worse. In fact, here, as before stated, by forcing the exchange of Queens, Black would have given himeself a fighting chance to save the game: 29...Be6!

The text is good enough. Threatens Nd7.

I was surprisingly offered a draw after this move, which I declined, which in hindsight was a mistake, I could have taken half a point and ultimately a win for the team, i have much to learn.

That was a very generous offer, as White has a winning advantage, here. Sometimes, though, it is not a bad idea to run by your team captain an opponent's draw offer.