Blimey, this could be a long answer! Because the London/Quins club has never had a settled home and has continually shifted from one part of town to another it has never really been able to lay down roots and build a community of fans in one particular location. There has never been a feeling that "this is my club, a club for life." Also a hand-to-mouth existence makes it difficult to spend the required amount of time and money on building that community link through schools development, etc. It takes time and effort for people to gain a sense of ownership of something, but the club has never really had the chance to do that.
One of the consequences is that there are fans all around London, and pockets of development work that have been built on or sustained by local community clubs. But there has never really been a ground zero if you like, an area that was the centre of development work. I personally don't watch Harlequins, it's too heavily rah-rah associated for me. I go and watch the Skolars sometimes but it's a two hour journey from my house the the ground, which incidentally is one of the problems for RL in London, it's too big and unweildy for one RL club to lay calim to, there is no commonality between people from different parts of town. For example, I'm a west Londoner, and until I met my girlfriend four years ago had only been south of the river a couple of times. Now, after four years, I've been there a million times but I still make jokes about needing my passport and jabs.
In north London, the London Skolars are doing it all from the bottom upwards. They are working hard to get a decent team on the field and doing the hard work in schools, colleges, etc. It's a long term game plan, but they have guys running the club that have a background in the City and they can see the value of doing it this way. I tend to think they will be successful, but it will take a long time.
The Storm are similar in a way, although they have come from a different angle. A few years back they moved from playing in the RL Conference (a comp for non-heartland teams) into the new NL3. But after one year they pulled out, which caused a few problems at the club and arguments. Some wanted to build and go for the big time, others (led by Paul Brown, the new Quins CEO) reckoned it was better to spend that money on the kids and developing the roots. This has proved to be a blessing, because they now have schools work feeding into five local clubs, who in turn feed into the Storm. And this is set to expand in the coming years.
Now, the Storm are by no means ready to enter a team in ESL at the moment, but I think the game is at a tipping point. We are on the verge of seeing kids who have grown up with RL becoming adults, and hopefully continuing to play RL. This is how sustainable clubs are built. The game finally seems to be building a collection of clubs and development programmes in one locale; south London. Now, Quins have a hard core of 3,500 who follow them all over town, if, in say, five years time they were to merge with the Storm they would bring that group of fans with them, add to that the fact that Souths are building a real RL community, then you perhaps have the basis of a sustainable professional club.
It's hypothetical, but I can certainly see it as a possibility.