JYS in F2 Brabham, 1970

Whilst checking out some of the background on that 'Jackie Stewart tests the DeTomaso" thread i was wondering, anybody here know what the background was to JYS's F2 drives for John Coombs in a Brabham in 1970?

Just a guess, but maybe Jackie arranged it as a fallback in case Ken couldn't get funding for 1970? "Faster!" makes it pretty clear that JYS was considering several F1 options if he had to leave Tyrrell - McLaren and Brabham for two - but for various reasons they all fell through, so JYS and Ken were forced down the March route (after false starts with BRM and Lola) - Ken was only certain of continuing after Dunlop reversed their decision to withdraw from F1. Thus, March was a last-minute decision and deal - by which time all the best seats were long gone.

Jackie had driven for Ken's Matra International in F2 in 1969 - that option didn't exist in 1970 and Jackie speaks favourably of John Coombs in "Faster", ranking him with Ken and Big Lou as a cool head in a crisis.

Incidentally - in "Faster" JYS records how he spent May 25th 1970 at Crystal Palace "with Ken, scouting around for a replacement for Servoz-Gavin." No mention of winning both his heat and the final of the Alcoa Trophy in Coombs' Brabham....

I'm intrigued, given Coombs' reputation, why he didn't go further in the sport- it seems as though he would've been quite capable of running a competent points-scoring private team in the World Championship in the mid/late 60s with a good driver - lack of ambition or funds or just that he enjoyed the less pressured life elsewhere in racing?