Earwig, I think the lse market cap is updated monthly. At some point ESP will be pushing for FTSE 250 inclusion. I don't think they will need to raise as much equity as you suggest- if I recall correctly their LTV ratio is below target and they will probably raise some debt.
i would make the bond 60-65 for what its worth
interesting to see where the retail bond will open. Last trading at about 38p and a thin market but not shorted.