While smartphones remain the dominant device in terms of UK mobile ad impressions, with a 74.1 per cent share, tablets are catching up fast, according to a report from mobile ad network InMobi.

The UK edition of its quarterly InMobi Insights report revealed that tablets and other connected devices together made up an 18.9 per cent share of impressions during Q3, 2012.

The iPhone continues to be the single most popular handset, with its various iterations making up a 27.9 per cent impression share. The iPad dominates the tablet market, meanwhile, with 11 per cent of impressions – thats an increase of 43 per cent from Q2.

“In the UK, mobile ad growth continues to be driven by smartphones. However, it is estimated that there are 5.9m tablets in the UK, and that number is likely to increase to just over 10m by 2013,” said InMobi head of UK sales Lee Blyth. “What these figures demonstrate is the huge opportunity for mobile advertising on smartphones and tablet devices in the UK. The onus is now on premium publishers to host and advertisers and marketers to create more engaging, interactive rich media ads across a variety of devices.”

The research also found that the mobile web accounts for 70 per cent of total impressions – but as in-app ads have grown, that share is dropping, down from 72 per cent in Q2, and 76 per cent in Q1.