On the left, the ESB I drank between Surbiton and Clandon. On the right the Old Peculier I am drinking now. The Brooks Moorgate briefcase is not only a stylish and useful bag that is "compatible with common British folding bike rack clips designed for attachment to the front of the bike" it also includes "a four-way stretch outer side pocket for carrying a bottle or thermos on the side". As my photo illustrates this four-way stretch outer side pocket is perfectly proportioned for a 500ml glass bottle containing the sort of bottled beverage one might pick up at a railway station.
The last ESB I had was a rather butch and hop-heavy cask beer. This bottled version has subdued hop. It's so long since I had an Old Pec from the cask that I can't begin to compare it.