No, it has a fairly tight catchment for year 7 intake. However, we got dd in from a waiting list in year 9 (she was out of school for a term) and I'd always encourage people to look at this option later on if things don't work out at the school you've chosen.
When we were looking for ds2 we really liked the Norwood school (just near the top end of Streatham common). It's smaller than quite a few others, has great buildings and a really nice atmosphere. They also have a catchment you'd fall outside of but they select 10% for ability in dance, art and music.
Kingsdale where my 12 year old goes (and where my 10 year old will hopefully be in September) is doing really well (bar the double stabbing in November 
It's in the top 20 oversubscribed schools in the UK. They select by lottery and also 15% by aptitude for music and sport so have no catchment. It only takes my ds 35 minutes to get there door to door and he's coping ok with the travelling.
If I was doing it all again for dd I'd have picked Norbury Manor over Harris for year 7. Know quite a few people with daughters there who feel it's a nice school. I really have issues with the highly sexualised and aggressively sexist culture in some of our mixed schools in South London. My daughter was exposed to some vile language and behaviour at Harris - kids watching porn on their phones in the playground, a boy in year 8 sexually propositioning her in a really explicit way when she was just 12. She's a tough kid and not in any way shy, but it reduced her to tears.
Sorry - not meaning to scare monger because I know bad stuff goes on in all schools. It's not a specific Harris issue. I do worry about gang culture. My children are mixed race and it's a real thing to them. There some really sexually exploitative, violent and nasty behaviour going on in some groups - it's more of a problem in South London than many people realise. Much as I like the area I would always choose to educate my daughter in a single sex school, and my boys in schools which are more reflective of the London wider demographic than of the area immediately surrounding my home. Kingsdale seems to have lots of nerds, very bright m/c children and eccentric kids, as well as lots of kids from tough estates from Peckam and areas like that. It's a proper comprehensive that really does cater for all social groups and all abilities. It also seems to have a reputation for turning out happy kids, and for me that's more of an issue than the GCSE results.