Partly in response to this
combined with nightly bathtime for little one, I've set up a bath siphon to a water butt, with of these porous pipes leaking it slowly into the flower bed.
Anyone used one before? Are they better buried, or on the surface of the soil? Not sure with London water whether it will clog with limescale if allowed to dry. We're not using it with soapy water, before you ask :)
The siphon is a £10 Burgon and Ball kit, and so far I highly recommend it if you are thinking of doing the same.