Another Instructive R+P Ending

GRANDMASTER Nigel Davies in his DVDs for ChessBase often lays great stress on the importance of pawn islands, implying that to have more than the opponent is to be at a fairly serious disadvantage.
I do not know of any other player who emphasises this point so much - perhaps it is part-and-parcel of Davies's positional-based approach compared with other players who are maybe more concerned about dynamics.
Last night, playing for Battersea 2 in a London League division three match against Greater London, I got down to a rook-and-pawn ending in which I had four pawn islands, three of them consisting of isolanis, against my opponent's two.

White to make his 23rd move in Nigel Blades (178) - Spanton (171)

How big is White's advantage? Is White already positionally winning or is his advantage largely cosmetic?
According to my main analysis engines, Komodo9 and Stockfish10, the position is almost dead equal.
After the practically forced …
23.g3
… the engines agree White's edge, if it can be called such, is worth about a tenth of a pawn - less than the edge computers reckon White has at the start of a game by virtue of moving first.
23...Rg5
The pawn ending after 23...Rd8? 24.Rxd8 Kxd8 25.Kc2 Kd7 26.Kc3 is difficult for Black - those extra pawn islands really start to count.
24.Rd4 Rd5?!
Simpler is 24...Rh5 25.h4 Rf5 when Black's h pawn may still be a theoretical weakness but is very hard for White to get at.
25.Rh4
I assumed 25.Rxd5!? was just good for me as Black gets a protected passed pawn, but the engines believe the pawn ending is drawn. Indeed there are lines where White threatens to win by getting a passed pawn on each flank.
25...h4 26.Ra4

Black has several moves that maintain equality

26...a5
I played this almost automatically, but it is by no means the only move.
The engines' main line runs 26...Rd2!? 27.Rxa7+ Kd6 28.Rxh7 Rxf2 29.Rxh5, which they reckon is completely equal despite Black's pawn minus. The text and 26...Kd6 are also equal, according to the engines.
The one plausible move they do not like is the passive 26...Rd7?! when White can begin to make progress with lines such as 27.Kc2 Rb7 28.b3 Kd6 29.Rd4+ Ke7 30.a4.
27.Kc2 Kd6 28.Kc3 Re5
This is probably OK but again there was a simpler solution, namely 28...Rf5. The point is that White has very little chance of making progress if he is obliged to play f4.
29.Rf4 Ke7 30.Kb3?!
This decentralisation seems to be a mistake. White should have temporised with his rook, or played for a passed a pawn with 30.b4. The engines reckon the position would still be equal, but a passed a pawn would at least mean Black could almost never afford an exchange of rooks.
30...Rb5+
This lets White off the hook. Correct was 30...Re2, eg 31.Kc3 e5! 32.Rf5 Ke6 33.Rxh5 Rxf2 when Black's more active pieces give a slight edge, according to the engines.
31.Kc3
I was worried about 31.Ka4? 32.Rxb2 Kxa5 but it seems I seriously misjudged the position. White's decentralised king gives Black an advantage - a winning advantage, according to Stockfish10; 'merely' plus-over-minus according to Komodo9.
31...Kf7?
I did not want to give White a second chance to go for the previous note, but decentralising the king means Black is now in big trouble.
32.Rc4 c5??
Probably best was 32...Rb6, when 33.Rc5 a4 gives Black counterplay. But White does not need to rush. Better is 33.a4! when Rc5 really is a threat.
33.a4 1-0
A sudden finish. There is no doubt the extra pawn islands made the ending more difficult for Black to play, but it seems the position should have been fairly easily drawn. As it happened, I even missed a chance, at move 30, to gain an edge.
Updated statistics
Battersea 2018-19
Event...Colour...Grade...Opponent's Grade...Result
CLL........B..........167...….........196...............…D
LL...…….B...…...167...………..159...………….D
CLL...…..B...…...167...………..161...………….W
CLL...…..B...…...167...………..190...………….D
LL...…….W...…..167...………..161...….………W
CLL...…..W...…..167...………..148...………….D
CLL...…..W...…..167...………..165...………….W
CLL...…..W...…..167...………..160...………….D
CLL...…..W...…..167...………..159...………….D
LL...…….B...…...167...………..168...………….D
LL...…….W...…..171...………..159...………….W
CLL...…..B...…...171...………..198...……….….L
CLL...…..B...…...171...………..169...…………..L
CLL...…..B...…...171...………..196...…………..L
LL...…….B...…...171...………..182...…………..D
CLL...…..W...…..171...………..189...…………..L
LL...…….B...…...171...………..178...…………..L
Overall this season for Battersea I have scored +4=8-5 for a grading performance of 170.
In season 2017-18 I scored +10=8-9 for a grading performance of 175.