The survey found that salaries in 2017 for chief strategy officers range from £180,000 to more than £250,000, while chief executive pay ranges from £200,000 to £350,000.
The Longhouse attributes the narrowing of the gap to an increased emphasis on data planning, ROI and proof of effectiveness.
Elsewhere, managing director salaries were between £150,000 and £200,000, heads of planning attracted pay of £120,000 to £180,000, and planning and strategy directors commanded salaries of between £70,000 and £120,000.
On the creative side, chief creative officers' salaries had a higher starting point than those of chief executives, ranging from £250,000 (against £200,000 for chief executives) to £500,000. Executive creative directors and creative directors attracted pay of between £90,000 to £250,000 and £50,000 to £90,000 respectively.
Five static years
Meanwhile, comparing 2017 data with The Longhouse's 2014 salary survey, revealed that while chief executive and managing director salary bands were identical, chief strategy officers are not as well remunerated five years ago (£160,000 to £200,000), while heads of planning were paid between £120,000 and £150,000.
Client services roles are defined by broad salary bands. Business directors, senior account directors and account directors drew salaries ranging from £65,000 to £100,000; £50,000 to £65,000; and £38,000 to £50,000 respectively in 2017. Five years before, those equivalent salaries ranged from £65,000 to £100,000; £50,000 to £65,000 and £36,000 to £50,000.
Helen Kimber, managing partner at The Longhouse, said that while a few years ago, the top salary bands for most roles would have corresponded to above-the-line agencies and those at the bottom to digital, direct and integrated agencies, the "cross pollination of skillsets, digitisation of the world we live in, plus the desire for polymaths is dissipating that".
Two sides of the coin
Kimber said that, overall, the survey findings were both encouraging and disheartening.
"Investment in strategic thinking at a senior management level is testament to how our business is evolving and changing; how we can be genuine partners to commercial businesses and less of a service industry," she said.
"The flip side of this is the stasis of salaries over time, we are losing the incentive to move up the career ladder and become future business leaders."
She said that agencies must focus more on developing staff skills and imbuing greater loyalty in order to reduce churn and save money.
The Longhouse mined data from its 5,000-strong contact database, with supplementary information gleaned from the 1,500 people it meets every year.
The company also collates salary information from the briefs it receives from the 50-plus networks and agencies spanning broadcast, content, digital, media, PR, experiential, branding and publishing.