I couldn't find much online about it so I thought I'd ask. On Marshall road someone painted 574m on the wall. From Google Steet view it looks like it was done between 2012-2014. So I was thinking maybe related to the Olympics. But from older photos the line becomes an arrow on the ground and points back towards Leyton.
This guy says: "It's unclear why someone's painted "574m" in giant letters on the wall by the allotments, although the equally giant arrow pointing in the general direction of Leyton station suggests a Games-time waymarker. Almost nobody walked instead via Asda's car park, past the ill-fated Leyton Food Market, although that route was deliberately upgraded too. The Retail Park now has a proper entrance off the High Road, down steps rather than a narrow zigzag ramp, which is yet another positive outcome from the Games."
https://www.flickr.com/photos/dgeezer/8045128301
Seems like a reasonable answer and it seems to be about 574m to the high street though quite a bit further to the station. Also, still doesn't really answer why they would opt for something so permanent at such specific distance. Any one have any more info? maybe anyone who attended the olympics?