Parkrun is a free, volunteer-organised 5km run. They take place every Saturday morning at 9am, in parks all over the country.
The idea for parkrun started in Bushy Park, London in 2004. It grew fast; now thousands across London start their weekend with a run.
I recently completed an unofficial challenge that people call 'LonDone' — that is, running all the Parkrun events in the London area.
Going by the strict definition of the Greater London Boundary, that's 47 different parkruns.
My first was in 2011. Between then and 2014 I did a few other in London — what's known as being a 'parkrun tourist'.
It wasn't until 2015 that I decided that I needed to complete ALL of the London parkruns. And so I set about doing it for the next 18 months. I'd save my local run (Crystal Palace) until last.
Here's what I learned along the way.
London's quietest Parkrun...
If you want a chilled start to your Saturday, try Pymmes Park in Enfield.
A beautiful little park with a tiny but uber-friendly group of people. Run here and, even if you're not that fast, you'll get a high ranking due to the small turnout...
...and London's busiest
By far, the busiest parkrun is Bushy Park. After all, this was where it all began.
It regularly gets around 800 people every week. Moreso on the anniversary (first week of October) of the first event.
London's hilliest parkrun...
If you're looking to improve your hill running, well, the clue is in the name: Hilly Fields parkrun in south east London has a steep incline at the end of the lap that'll sap your energy every time you do it. Gladstone and Crystal Palace also have steep gradients to challenge you.
... and London's flattest
It's Burgess Park in Camberwell. A flat run a couple of times around a lake, come here if fast times are your thing. Hackney parkrun comes a close second, being mostly alongside a flat towpath.
London's friendliest parkrun
This is of course, highly subjective. But for me, it's Old Deer Park in Richmond, where I was also thrilled to meet the founder of parkrun, Paul Sinton-Hewitt. He was awarded a CBE for his efforts.
Also a genuine honour to meet @paulsintonhewit at Old Deer Park this morning. Thank you, sir. #loveparkrun pic.twitter.com/NutK6gjpUj— Geoff Marshall (@geofftech) December 10, 2016
They also have a 'tea fund' jar which means that one week, you may find there's enough money for a free cuppa!
London's Dog-friendliest parkrun
We found Bexley parkrun to be the one most favoured for running with your canine pal. Must be kept on a lead though — one of the few, but strict, parkrun rules.
Parkrun with the best views of London
There are two, and it's hard to pick between them. In the north, Ally Pally parkrun provides stunning views. The elevation gives runners a great view looking south across London at the highest part of the course.
Ally Pally complete with @dectoman #loveparkrun pic.twitter.com/6CL890QXoQ— Geoff Marshall (@geofftech) December 31, 2016
Roundshaw Downs in the south also offers fantastic views looking north into London town.
London's prettiest parkrun...
This one might surprise you — go to Peckham Rye for a twisty course, with ornate flowerbeds, ancient trees, and something new to see at every turn. Which means it's certainly never dull, unlike...
... and London's dullest parkrun
Sorry, Walthamstow that would have to be you. It's three laps around a sports pitch... a bit like being back at school again.
London's best post-parkrun cafe
Yes, it's common for parkrun runners to have a post-5km coffee or tea afterwards. At the Osterley parkrun, though, you get to go to Osterley's revamped stables to refuel — a stunning building with great facilities.
The parkrun we never want to relive is Lloyd Park in Croydon. They hold cross country meets here because it's rugged, bumpy, all on grass, with crazy hills and undulating gradients. It's London's toughest course (especially after it's been raining). Not for the fainthearted.
Find out more on the parkrun website.