It's not intended to be comprehensive and indeed omits Soho, Westminster, Lambeth and other central areas.
Amongst all the trendy food & drink outlets such as the Belgo chain (mussels, chips and Belgian beer), the Chez Gerard posh-nosheries or the Fish!Diners, the real ale pub scene is surprisingly limited in beer varieties but nevertheless there are many pubs well worth visiting.
Branded pubco outlets such as All Bar One and Nicholsons (both Bass), Hogshead (Whitbread) and JD Wetherspoon predominate. Amongst brewers, Youngs and Sam Smiths have many pubs. All these serve mainly the "usual suspects" in beers - in each chain you'll see much the same each time. However there are a few gems serving beers from small breweries.
This article concentrates on pubs suitable for a quiet sit down whilst visiting for the day, rather than other types of pub.
People not used to visiting London (and there still seem to be plenty of those) often say they're put off by various factors. Certainly getting about can be somewhat daunting when you're not used to it but provided you're not in a rush and not travelling at a peak time and have good Tube and surface maps, there should be no problems in that respect.
A common mistake is to arrive on a Tube platform and rush onto a train standing there. For those in doubt, it's usually much better to wait for the next train and take the time to plan. Most (all?) Central London Tube stations have displays for the next two trains.
Admittedly as of November/December, complications from the Hatfield disaster change things in this respect. The rest of this article will assume that travel is back to normal!
The Tube is divided into travel zones. For the purposes of this article zones 1 and 2 are all that's needed and the LT Travelcard price above is for these zones. Zone 1 is the Circle Line plus all stations inside it. The WAGN card covers zones 1-6.
There are links at the end of the article to more detailed information.
With a Travelcard one doesn't have to think about tickets during the day so it's much less of a problem if you take a wrong turn or are forced to change your route. The Tube network does suffer from unexpected blockages and closures so it really helps to be flexible in routes and times.
For Saturday, the 09:15 non-stop Cambridge Cruiser to Kings Cross is particularly convenient, arriving about 10:00 - a good time for getting to many attractions early and avoiding the crowds. The Liverpool Street 09:05 is also a good choice though slower.
Bear in mind that many attractions (other than shops) are busier on Sunday than Saturday.
The return journey can seem slower as there tend to be fewer non-stop trains and the trains are often fuller.
Many fine, historic pubs in London are under threat as property values make land more valuable for other purposes. Meanwhile Bass, Punch Taverns and the other fizz-obsessed chains are busy ruining fine pubs by rebranding them to short-lived, trendy youth themes. (An all-too familiar story.) What's Brewing November 2000 has a major feature on London pubs and trendy bars.
Most of the pubs mentioned here open at 11am Monday-Saturday (noon on Sunday) and are open all afternoon.
Part 2 of the article covers two of the most interesting areas for real ale pubs in Central London: Southwark and Covent Garden.