Data gathering from public websites

From an English law perspective, is a business allowed to gather data from public websites for commercial purposes, where that website's terms and conditions do not specifically disallowed this? Or where the website does not have terms and conditions at all? Also, if a website does not have terms and conditions, but has a general copy right notice (e.g. "XYZ 2016 All rights reserved"), does this mean that the data cannot be reproduced?