When Stella Cox first started trading in the Islamic equivalent of the conventional money markets in 1984, there were just a handful of transactions on a weekly turnover of $50m. Some days, not a single deal was done.

Today, that trickle has become, if not a torrent, then certainly a substantial flow, with turnover estimated at $3bn a day through London – the main centre for short and medium-term Sharia-compliant financial transactions.