The bank said the growth was a result of a 26% increase in gross organic origination which hit £1,229m, up from £973, during the same period in 2016.
Profit before tax increased by 20% to £78.4m while share prices rose to 3.5p per share, up from 2.9p in H1 2016.
Andy Golding, group chief executive, said he expects to deliver net loan book growth of at least high-teens in 2017.
He added: “We continued to successfully navigate significant regulatory and tax change impacting the buy-to-let market in the first half, delivering 26% growth in total organic origination versus the first half of 2016. We also generated a 20% growth in underlying profit before tax and a best in class return on equity of 28%, whilst maintaining our strong cost discipline and deep understanding of pricing for risk.
“We further strengthened our capital base through the issue of £60m of Additional Tier 1 securities in May 2017. I am delighted with the credit performance of the book, with a loan loss ratio of 4bps in the first half, reflecting our robust underwriting standards, lending criteria and sensible loan to values.”