Sure, in this area of London there are a number of stunning pubs, but the Kings Arms is one of the best and holds a special place in your author's heart as it was here that he drank on the first evening he moved to London.
The pub is not unusual in London in that it serves Thai food, but the Thai food here is pretty good and reasonably priced so your author can't even fault it on that. All in, it's a very accessible Central London pub with atmosphere which is far enough away from the hustle and bustle you find North of the River to make it very pleasant. It's well worthy of the various accolades it has won from pub and beer guides over the years.
For more information on the Kings Arms, and a map, have a look at the page on the London SE1 site at http://www.london-se1.co.uk/restaurants/info/244/the-kings-arms