What is the percentage of me being robbed of my DLSR in london?

I'm born in London and not a tourist, I know london isn't as safe as it used to be but my aunt is taking it slightly too far.

She doesn't want me to wear my small nikon DLSR around my neck as someone apparently could "cut it off my neck" lol or injure me to take it.

It would only be around central london for a bit to take shots/video.

I will remain vigilant and careful where I use it, please tell me she is being slightly paranoid?

Who really knows about the risk. If I were you I'd just put my dslr in a woolly hat/beanie and that in a backpack or rucksack. Easy to get out when needed and your camera will be relatively safe when not in use.

More than slightly paranoid.

What has this got to do with travel?

Very little chance at all in central tourist London

Better than your chances of winning the lottery.

Not really a problem other than marking you out as a potentially dumb tourist who thinks everything is fine
It's this years £1,000 smart phones they want to steal. Ebay and camera shops are stuffed full of old photo enthusiast grade DSLRs. Keep your wits about you and don't be where a bunch of thieves on a very crowded street can easily jostle you.

Nobody could make an even approximate prediction of one particular tourist being robbed of a valuable, neck-hung, item while in London. It would depend partly in which parts of London you visit.

Very low if you use a bit of common sense.