when i lived in Tulse Hill, i far preferred Castello's for my fry up's, which may sound like blasphemy to you, but i think with good reason.
Although a Portuguese restaurant, they do a English fry up very well, and the sausages and bacon were always very high quality. The portions are a beast, you'll struggle to finish a Jumbo English, which comes with free high quality coffee, toast all for £6.
Also they serve Portuguese beer, Super Bock or Sagres, which only costs £1.80 per bottle. So you can have a beer with your fry up, which is exactly what i want to do on a Saturday morning.