, the pureplay specialising in plus-size fashion, notched up a like-for-like sales rise of 61% over the peak period.

The etailer, founded by veteran fashion entrepreneur Gifi Fields, achieved a conversion rate of 4.3% in the six weeks to end-December, when 40% of sales were made to repeat customers.

Fields said: “November was very strong, driven for us by new customers, culminating with Black Friday weekend.

“December was a very strange month – a lot of volatility and a fall off of demand for full price.

“The new norm for pureplayers is that the Boxing Day Sales gives a second bite of the cherry. Our biggest trading day of the year was December 27 when we launched our Sale.

“We are particularly pleased by the attraction of so many new customers while retaining the custom of so many that have purchased from us before.”

The figures reflect the performance of, and do not include sales of its product through retail partners such as Debenhams, Evans and Next.

In the half year to May 31, 2017 – the brand’s first six months of trading online – Scarlett & Jo’s revenue climbed 500% year on year to £3.5m.

The etailer aims for a big slice of the plus-size market, which last year GlobalData estimated accounts for £1 in every £5 spent on womenswear.

Spend on plus-size clothing has risen by £800m since 2012 and the market is now worth £5bn.

Fields expected 2018 to bring “challenging” conditions. He said: “We have lots to build on and so very much to do.”