The eight-storey building, developed by M&G with development manager Bell Hammer, is due for completion in August 2015 and is the second of three buildings that comprise the 600,000 sq ft Forbury Place. SSE is understood to be paying close to the £34 per sq ft quoting rent.

M&G Real Estate, a major investor in Reading, has invested nearly £200m in the town centre in 2014 – including the acquisition of One Reading Central, a 220,000 sq ft prime office scheme, the purchase of R+, a Grade ‘A’ 100,000 sq ft office development, and 15,000 sq ft of lettings at its Apex Plaza complex that took the building to full occupation.

According to M&G Real Estate, demand remains strong for core south east business premises, particularly for grade ‘A’ buildings in close proximity to major transport hubs.

Reading in particular is becoming increasingly sought after thanks to its fast train link to London and enviable location on the motorway network.

Aaron Pope, Director, Asset Management at M&G Real Estate, said: "We are delighted that our decision to lead the speculative office development in Reading has resulted in letting the entire building to SSE. We are confident that our strategy of building West End-quality buildings in Reading will attract and secure further occupiers to a location that grows from strength to strength."

Joel Hawkins, Principal at Bell Hammer, adds: “Forbury Place stands out in the Thames Valley as a development of exceptional design on a significant scale. To secure a letting of this size to an excellent covenant, before completion of the building, is an excellent result and bodes well for the development of the next phase of the scheme, Number 2, Forbury Place.”

Alistair Phillips-Davies, Chief Executive of SSE, said: “We have looked extensively for the right building in the right location to provide a high quality environment from which to support efficient operations for customers and provide the right base for our extensive activities across the south east of England; and we have found it in Number 1 Forbury Place.

“The new building gives us the space to bring together over 1,900 SSE employees in one place and provide a modern, flexible working environment. SSE is a major service provider in the south-east of England and this is an excellent opportunity for us to bring together our staff from across the company in a new central hub from which to build further our business in this economically vital part of the UK.”

M&G bought the site in March 2012 from Scottish Widows Investment Partnership and subsequently agreed a lease surrender from Cable & Wireless on the existing building, Energis House. It obtained planning consent for a 380,000 sq ft redevelopment across two buildings in April of 2013.

The scheme is designed by Aukett Fitzroy Robinson and was the first significant speculative office development commitment in the Reading office market post the downturn.