They were intended initially for the wealthy investor, who had access to a diverse range of assets, and wanted to put these assets to good use.

The first Sipps were designed for an elite band of investors but they soon took off because they were not bound to invest in the company’s own investment funds, and savers could put shares, property and other assets into the pot.

But Sipps have come under scrutiny in recent years.

As they have become more accessible to people with limited funds, so advisers have found them popular products to recommend and the regulator has looked closely at how they are being sold.

The FCA is currently undergoing a thematic review, the results of which are due to be released shortly, which will determine the future regulation of Sipps.

One of the biggest concerns is the capital adequacy of Sipp providers. There are so many companies offering Sipps, some of which are small and for whom Sipps barely register on the radar, and the FCA is worried about the prospect of Sipp companies failing.

There are concerns in the industry about more esoteric products being put into Sipps, and whether the wrong products are being sold to unsuitable people.

As the financial services industry is getting to grips with the latest earthquake in pensions, namely the ban on compulsory annuitisation, so the Sipp sector is preparing for its own dramatic changes.

Melanie Tringham is features editor of Financial Adviser