English v Flank Openings: How to lose from a winning position!

I've been playing the English Opening for many years and have played it with confidence, usually finding players meeting 1. c4 with either 1....e5 or 1. .....Nf6.But in my last two match games I have faced 1.....b6 and found myself in a middle game where my opponents blundered but I failed to capitalise on their errors. So, it may be instructive to see how this happens.....

A few days later we had a league match against Stroud Cubs.

Two games with a similar start in which I overlooked the best move in a crucial position. Whyt does this happen? We play long matches in the evening and one inevitable suffers from tiredness, which affects the ability to analyse. I often find that a stimulus (ie energy giving drink) can help, but what is best? When I have a "red Bull" I often win; a glass of milk leads to a draw and a pint of beer leads to an exciting game in which I invariably make an error in the middle game. Coffee can be a good stimulus but in the second of the two games I have posted here the Guinness Coffee Drink may well account for the outcome, along with the cramped seating and occasional visits over the boards from tiny fruit flies that would land on the pawns and the coffee drink! In spite of this, Stroud Chess Club was warm, welcoming, friendly and a great place to play a chess match!

As a postscript, (or should I say "Post Mortem"?) I might mention that I usually write up my games into a scorebook, and use the chess.com analysis and game review features to note the strengths and weaknesses of the moves played. Here is an example, with colour-coded ratings and all...

(This is my first BLOG on chess.com so I hope that it may be of interest. Thanks to Benjamin Lappin for advice on how to set this up)

Feedback very welcome.

Clint Mann