In the fourth quarter firms wrote 5% more business than in quarter three, and 9% more than in the final quarter of 2013.
John Heron, managing director of Paragon, said: “It is encouraging that confidence among intermediaries has increased since Q4, giving a strong platform for the mortgage market for 2015.
“The increased levels of business firms have been writing is a positive sign of growth, providing evidence of a busier market in Q4.
“This does not seem to be the case on an individual basis however, suggesting the process may be more complex post MMR with advisors working harder to take advantage of growth opportunities."
First-time buyers saw a 1% increase in business in quarter four to take up 19% of the market.
Nearly half (48%) of intermediaries said the availability of buy-to-let finance has improved since the third quarter, while 35% reported 'strong' or 'very strong' landlord demand.
Looking ahead four in 10 (41%) brokers expect to conduct more buy-to-let mortgage business over the next 12 months.
Heron added: “Another good sign is the balance of intermediaries expecting buy-to-let lending to grow further over the coming year.
“This is likely to be driven by the competitive market and strong demand seen over 2014, which we anticipate to continue through 2015.”