How Can You Grow Your YouTube Subscriber List Organically?

Here is my YouTube channel.  It houses a variety of vlog-style videos, family activities, a new venture called #vlogchallenge and a bit about my love for stationery.  I plugged into a free webinar recently which was based around growing your channel organically. There was nothing to lose really (apart from an hour of my time).
YouTube, subscribers, organic,

SPOILER ALERT:  Apparently, the answer is that 'collaborations' are the way to grow your channel. Jamie Oliver was used as an example of channel growth based on the premise that that he had a "show on a local channel in the UK" and then used his own money to move that over to a YouTube audience with the help of a production team. His collaborations had been with Kevin Bacon, Grover from Sesame Street and the cast from an American food network show. The spike in his subscribers (and view count) after these collaborations was considered to be a success.

It was later explained that Jamie Oliver is quite well known (with successful restaurants and book deals) in the UK which is when myself and Kate (who was also listening in) started to think that the webinar was aimed at people who already had a lot of subscribers and they had successfully montized their videos on YouTube to the point where this was a main income stream. They were in a position where they were able to invest their time in actually go to see other people who had a lot of subscribers (we're talking in the high thousands here) to create their collaboration videos.

I mean, can you imagine this happening:
Hi Kev, What's in the shed? Oh hang on... is it Jamie Oliver? Haha, just kidding. Will you nip up to Blackburn and join me on #vlogchallenge this week?  You will? Cheers, buddy. No, sorry, I can't pay any expenses. What's that? Kevin? Kevin?  Where have you gone...
No, neither can I.

One of the questions I ask myself often is, "Why is YouTube so popular?" and I can break it into three themes: music, creativity and conversation.  And the third theme is the reason why vlogging (or talking direct to camera) is growing in popularity.

Vlogging is currently at the forefront of YouTube channel growth with many young vloggers taking over the platform with their bubbly, enthusiastic personalities. Some of these young people are now branching out into further media after being offered television presenting slots and radio shows; the focus being very much on the 11-16 and 16-24 year old age groups.  

Online relationships often mean that peer groups are now not necessarily formed at school or work. They are also very often not people who live in the same town as you. Those not earning a true income stream from YouTube monetization can not afford to take time away from their job or family to arrange collaborations.

So my new question is: How can start-up channels really grow their YouTube subscriber list organically?

Have you grown a YouTube channel from zero to hero? How long did it take? Do you have any hints or ideas? 
Do you want to pop over to Blackburn and collaborate?