Can't believe I'm starting a thread for this, but anyway...

As some of you might have seen, I had a lovely date with a lovely lady on Thursday. Took a punt and asked her if she fancied hanging out on Saturday. She said yes!

But, on such a sunny Saturday day in London I haven't got a scooby what to do. She's not from around here, so touristy (but not TOO touristy and definitely not too busy and hectic) and non-touristy ideas could both work, but ideally think it'd be cool to do something outdoors. Unfortunately the usual online guides aren't offering up much inspiration

Any suggestions? Constructive and comedy ('take her up the oxo tower' etc) ideas both welcome.