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.
The portfolio will be integrated into GRP-owned ABL Group, doubling the Belfast-based broker's GWP to £107m.
The broker also revealed a plan to triple its international turnover and to grow its position as a large independent European broker.
It is the broker's second deal since it was bought by GRP in 2018.
But the deal is still on hold as a November trial looms in the United States and the New Zealand Commerce Commission also raises competition concerns.
Linkscover provides insurance to many golf clubs in the UK.
CEO Phil Barton reveals how the recent Kudos deal came about and discusses how the purchase of a loss adjuster will enhance the broker's client proposition.
Group CEO Nick Houghton discusses how the Bickley deal came about and reveals plans to acquire 10 to 15 more businesses in the next three to five years.
Rock will continue to be managed as a standalone business under the leadership of MD Antony Martin.
The broker bought London-based ES Risks for an undisclosed sum.
MD Paul Younger says Castle has further deals in the pipeline as it targets £10m in GWP.