It's just out of area, but try a brisk walk to the Dolphin in Sydenham. Mayow Road, off Perry Vale, goes straight to it.
I went there this weekend and I couldn't fault it. Terrific roast beef, plenty of vegetables, and a well kept bitter - Adnam's Broadside. The size of the main room means although it was busy on a Sunday, it wasn't cramped and there are plenty of tables.
Been meaning to go for ages, and I was impressed. The Honor Oak has some serious competition!
Have been to the Dolphin before and it was so over run with kids running riot I found it quite unpleasant. However I might give it a go again. Went to The Amersham Arms opp New Cross Stn yesterday - cracking christmas roast special (carvery) and desert for ?7.50. If you get there between 12 -1 it is only ?5.00, or ?6 between 1-2pm highly recommended.