The Gateshead-based broker, specialising in third sector and small business risks, says the acquisition will help the family firm expand its national reach.
The broker says the business plans to continue to develop its expertise in areas such as property and construction as well as expanding into new markets.
Deal for Dublin-based Brassington Insurance is consolidator's sixth in the Republic of Ireland this year.
The broker is to buy the WTW treaty reinsurance operations following the collapse of the original deal.
The High Street business, primarily known for personal lines, is targeting to become a top ten commercial broker. Head of the unit, Richard Easterbrook tells Insurance Age about the plans.
The sharing economy start-up has signed a distribution deal with the providers.
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The move follows deals to buy Bennetts and the brands Autosaint, Ladybird and First Van.
Shawbrook Bank supported the venture with a commercial loan.
Following its takeover by Intact, RSA's UK, Ireland, Europe and Middle East operations also reports gross written premiums of £2.3bn.
Acquisition provides further entry into Ireland and expands specialty expertise for the US headquartered business.
The Kidderminster-headquartered broker's specialisms include construction, motor trade, high net worth and unoccupied property and the deal brings 19 staff to Aston Lark.
The provider joins Let Alliance and HomeLet as part of the business’s rental proposition.
Three Sixty is based in Bolton and is a specialist private client broker.
Simon Matson, CEO, Europe, Middle East and Asia, said the UK division had seen organic growth of 9%.
The consolidator now places circa £900m in gross written premium and employs over 1,500 people in over 50 offices across the UK and Ireland.
CEO Robert Organ highlighted how recent buy, PI specialist Insure Risk, was a good fit for the business and chats through its move to join Jensten.
Aon, which abandoned its $30bn merger deal to buy WTW earlier this week, has shared its new leadership structure.
The move follows Tasker becoming part of the Jensten Group earlier this year.
Gallagher had been set to buy £3.6bn of WTW assets including Willis Re as part of Aon/WTW divestment plans ahead of their proposed combination.
Aon is set to pay a $1bn termination fee to WTW as CEO Greg Case says the two businesses "reached an impasse with the US Department of Justice".
CEO Maurice Boyd tells Insurance Age how the recent WTW purchase came about and outlines the GRP-owned firm's future ambitions.
Deal for Principal Insurance Ireland is the consolidator's fifth in Ireland this year.