Central and usually busy with an after work crowd, I like the Champion best at lunchtimes when the food is hearty* and you're more likely to be able to sit down somewhere.
With large stained glass windows downstairs, it's a traditional and pretty boozer to look at, but better still, it's part of the Sam Smiths company, so you can enjoy an inexplicably cheap pint, or even a random cola substance, whilst imagining that you're perhaps in some quaint part of the Kent countryside, rather than out back of Oxford Street.
I love Sam Smiths pubs and this one in particular, provided that it's not too busy, is tops.
*Ah, the highly memorable 'cajun chicken lasagne', there.