First of all, the significance: this position is from the game Pietrzycki v Rudd, from the Devon v Somerset match. The score in the other fifteen games was 7½-7½, so the match was to hang on the result of this game.The crucial factors of this position, as I see them, are the following:
1) The black bishop is both a better piece, and a currently better-placed piece, than the white knight.
2) The black pawns are far enough advanced that they might have a decent chance of queening; the white ones are not.
3) The white rook is somewhat awkwardly placed, although it does have the good point that while it's on a4, black always has to watch for the possibility of white's playing a3.
So my take on the position is that black has a definite advantage. Is it enough for a win? My gut feeling would be probably not, but in practice it's difficult for white to defend. Among my thoughts while playing this position was that while R+B v R is a theoretical draw, it is not an easy draw, and at 40/100 + G/20, I'd fancy my chances of winning it.
In the actual game, white played 49.Ne5, to which I responded with the natural 49...Bg7. Now white missed a trick here: after 50.f4!, it is hard to see how I make progress. (50...Rxf4 51.Nd3+ Kb5, for example, can be met by 52.Rxb4+ and that's an immediate draw.) In practice, I'd have probably gone for 50...gxf3+ 51.Nxf3 Rc4, and tried to round up the a-pawn. We would have probably ended up in R+B v R at some point.
But white's actual move was 50.Ng6?!, after which white has made things rather more difficult for himself. 50...Rd2 meant white had to deal with threats to f2 and a2: the way to deal with these was probably 51.Kg3, reaching a similar position to the last line. Instead, 51.Nf4? probably pushed the position over the edge.
After 51...Kb5 52.Ra8 (52.Ra7 comes to much the same thing after 52...Be5 53.Ng6 Bd4), I then played 52...Be5 to stop the king's coming up to snaffle the g-pawn. 53.Kg3 would have been met with 53...Rd4 54.Rf8 Rxf4! 55.Rxf4 Ka4, and the black pawn easily wins the race.
(The full analysis runs 56.Kxg4 Bxf4 57.Kxf4 Ka3 58.Kg5 Kxa2 59.f4 b3 60.f5 b2 61.f6 b1=Q and now 62. f7 Qb4/b8 and 63...Qf8, or 62.Kh6 Qf5 63.Kg7 Qg5+ 64.Kf7 Kb3 and white is stuck: Ke7/f7 do not threaten to advance the pawn, and Ke6 followed by f7 allows ...Qd8.)So white played 53.Ng6, and the game continued Bc7 54.Rc8 (what else? ...Ba5 was a serious threat whatever) Bb6 55.Ne5 Rxf2+ 56. Kg3 Rxa2 57.Kxg4. I'd managed to emerge a pawn up, and now set about shielding the b-pawn from any white pieces thinking of coming back to defend. 57...Rd2 prevented the knight's passage back to d3 (note that 58.Nc4? fails to 58...Rd4+). Thus white had to spend a tempo on 58.Kf3, after which 58...b3 59.Nc4 Rf2+ gave him an unwanted decision:
If white now plays 60.Kg3 (60.Kg4 is not all that different, except that it doesn't attack the rook.), then I play 60...Bc5, and the knight has nowhere good to go to escape the attack. Wherever it goes, I can play 61...b2. An amusing line is 60.Kg3 Bc5 61.Ne5 b2 62.Rb8+ Bb6 63.Nd7 (or 63.Nc4 Kxc4 64.Rxb6 Rd2 and my king snakes in to shepherd the pawn home) Rf6!, and the pawn queens.
So instead white tried 60.Ke4 Bc5 61.Kd5. Unfortunately for him, I'd already seen the answer to this: 61...Rf5+ 62.Ke6 Kxc4! 63.Kxf5 b2, with no way to stop the pawn queening. The game ended a few inconsequential moves later.
So in the end, I won the game and Somerset thereby won the match. (Yes, I play for Somerset, not Devon. It's because I lived in Somerset for twenty years before moving across the border.) Should I have won the game? Well, I suspect not. I get the feeling some of the contributors to the previous post would have put up a more tenacious defence than my actual opponent did.