It's all the hidden fees the NOMADS charge and the knock on effect of actually having to have a presence in London - "consulting with prospective investors" was always one I liked.
Your information is correct in that's what the "cost" is but it's like saying the cost of running an office is just the rent - it's not.
My source is personal experience - If TNG can maintain an AIM listing for <$1M per year (including listing fees, NOMADS, required investor seminar attendance, conferences and associated travel costs etc I'll take my hat off to them.
And we know they don't fly economy or stay in anything less than 5 star hotels