Rea Brothers made a pre-tax profit of pounds 802,000 in the six months to 30 June, compared with pounds 284,000 in the same period last year.
The group, whose activities include banking, investment management, corporate finance, and trust and company administration, raised the interim dividend by 20 per cent to 0.30p.
The firm made a pounds 175,000 exceptional loss as a provision against the bomb damage. Sir John Hill, the chairman, said: 'Although the Bishopsgate bomb incident in April necessitated our departure from Alderman's House for some months, there was no dislocation of service to clients.'
All the group's businesses contributed to the improvement, Roger Parsons, joint managing director, said.
Offshore operations in Guernsey and the Isle of Man produced record first-half profits. Fund management businesses also performed particularly well in the six months.
Bad debt provisions fell to pounds 21,000 from pounds 90,000 a year earlier. Banking and investment activity increased, offsetting the effect of low short-term interest rates on earnings from the group's capital, Mr Parsons said.
Earnings per share rose to 1.42p from 0.26p.