According to Crossrail and Savills UK Research, Crossrail will increase London’s rail capacity by 10% and bring an extra 1.5m people within 45 minutes journey time of central London. It will link key districts such as Heathrow, the West End, the City and Docklands. Commuters will see big improvements: for example the journey from Woolwich in South East London to Central London will fall to 19 minutes from 40 minutes.

Travel time to central locations is one of the key drivers of value for London property. For certain areas, Crossrail will make a massive difference, increasing demand for homes. Where development has already occurred, such as at the Royal Arsenal scheme in Woolwich, new build schemes have achieved a significant premium to existing stock.
http://www.savills.com.hk/blog/article/143631/hong-kong-articles/engine-of-growth.aspx