Prompted by an email from Colin I have now noted the new historic_betfair_win_prices pdf which contains an example of pulling BSP data.
I used that as a base ( the key new bit to me was the format of the join command )
So to answer my own original question above in case it helps others in future here is my sql to achieve an answer to the example / demo question above.
select meeting_date,scheduled_time,name,finish_position,starting_price_decimal,bsp
from historic_races
join historic_runners using (race_id) join
historic_betfair_win_prices ON race_id=sf_race_id and
runner_id = sf_runner_id
where course='newmarket' and trainer_id=152
order by scheduled_time asc;