Entry to research at later stage?

I never got into a bank, currently 28yo in the UK. Started out in fund research for an institution, and have spent the last five years interviewing and assessing fund managers, analysts and research notes. Currently at £100k total. I am sitting the CFA level 3 this year, got a good BSc and an MSc from a good London university.

The situation is, I still really want to do equity research. I keep reading terrible research from both buyside and sellside, and speaking to analysts and portfolio managers who lack even basic information about their investments. They are just clueless. Over and over. However, after a point fund research is pretty mind-numbing, because you keep seeing the same managers, writing the same format of reports, and changing jobs means whipping out the same exposition again. Hence the other side of that table seems as attractive as ever before.

The opps seem to be:

• Research assistant roles, of the "team secretary" type: these are advertised every now and then. How common is it to go from that into a real research position? Or perhaps the question is, how rigidly do research departments enforce their hiring templates?

• Advertised roles: if you work in research you know the typical job advert. I don't fit that template. Is there still a point in applying? Do non-HR people even read cover letters?

• MBA: I've been recommended doing the Columbia one for entry opps, and checking out the US would be pretty nice. I have however gotten some feedback from top European ones that would be keen to have me. I got a decent GMAT (96th pct) so could probably chance either. There's the issue of cost though. How good would a Columbia MBA be, vs other top tier MBA in terms of creating new entry opps at this stage? Obviously if there is no chance of entry at this point I'd rather go for a generalist MBA in Europe and fart around here for the rest of my career.

Would be quite appreciated.