In the second quarter of 2013, 23.2% of online sales in the United Kingdom were made through smartphones and tablets, exactly double the percentage from the same period last year (11.6%), according to the latest report from business and technology consultancy Capgemini and U.K. e-retail association Interactive Media in Retail Group (IMRG).

Additionally, the percentage of traffic to U.K. retail web sites coming from mobile devices grew from 21.1% in Q2 2012 to 34.0% in Q2 2013, the firms say. And the percentage of “click and collect” orders—when a consumer pays for an item on a mobile device and picks it up in a store—reached a record high, accounting for 16% of all e-retail sales in the United Kingdom in the quarter, up from 12% in Q2 2012, IMRG and Capgemini say.

“This correlation of mobile ordering and location-flexible collection is at the heart of the mobile Internet and the impact it will have on consumer behavior,” says Chris Webster, vice president of consumer products and retail at Capgemini.

Meanwhile, U.S. and U.K. affiliate network Affiliate Window measured more mobile sales through the iPhone in August 2013 than in the entire first quarter of 2012, it says. It does not report total sales. Consumers on iPhones made 135 purchases per hour via their devices in August.

While sales on iPhones were up month over month by 6.30%, sales on Android smartphones were down 31.86%, Affiliate Window says. Android conversions had been nearly identical to iPhone conversions in July, but fell sharply in August, the company says. Affiliate Window did not provide an explanation for why these conversion rates diverged.

For August, the network also reports:

• 19.84% of web traffic came through mobile devices, with 12.14% coming from smartphones and 7.7% from tablets.
• Mobile devices accounted for 22.27% of sales across the hundreds of sites in its network, up from 20.60% in July.