Architect RSHP has said it expects the UK and Middle East to have accounted for a greater share of its income by the time it publishes its next set of annual numbers.

In its latest accounts, the firm said turnover last year stayed flat at £25m with its biggest market remaining the UK with revenue of £7.2m, up 11% on last time.

The firm behind the planned extension to the British Library added that it had managed to shrug off the impact of rising costs in the UK: “The UK market has remained strong for us and we have secured more work than we had previously projected.”

The architect is behind a £400m proposal to extend the British Library

But it warned that overall turnover “will be lower than 2023 whist anticipating that costs will continue to rise due inflationary effects”.

And it said: “We have noticed that overall activity levels are reduced, new projects are slow to start and existing projects are subject to increased delays between stages.”

After the UK, its biggest markets are the Middle East and China. Turnover from the Middle East jump by nearly half to £6.4m but a slowdown in China saw work there fall a third to £3.3m.

Pre-tax profit was down a third to £2.3m with the firm putting the fall down to increased cost.