Moped muggers on the prowl in west London?

Sadly, the more bike-mugging or angle-grinding thefts stories appear (and and arrests and convictions for them don't), the more the low-lives are likely to think, 'Hey, there's an idea...'

Did you report it to the local Chiswick / Hounslow police?

It may also be worth reporting to Richmond Police / Royal Parks police in connection with the previous offences - particularly if there's scope to recover any CCTV that would show the face of the guy on the back of the bike.

Someone I know was mugged in Burgess Park recently for his road bike. He's a big guy and didn't want to give it up, but the two that attacked him initially were joined by two more, one of whom flashed a knife. So if you're riding through Burgess Park at night, be careful of the unlit stretch of path on the Camberwell side.

Been "buzzed" a couple of times recently in south London by pairs of mopeds whose intention seems to be to see if you'll fall and then grab the bike if you do. The camera didn't get the plates but as Awavey says, most likely false or stolen anyway. Exercising during lockdown when the roads were empty had several slow down alongside and give the bike a good once over before zooming off; I'd like to imagine it's because I look big, hard and ugly enough to be left alone but in fact possibly because they decided the bike's not worth it (it's a full carbon Ultegra Di2 but it doesn't have a big famous brand logo, plus I have a theory they regard rim brakes as   a sign of being old and/or cheap). Not a huge concern as yet - I'd be more concerned about being mugged when on foot - but certainly something to bear in mind when choosing a route and to keep an eye out for.

Highly suspicious. Thanks for the warning. Did you get the vehicle reg? Probably nicked as well.