The date of this advertisement is vital to understanding it. It comes from the Coventry Evening Telegraph of Saturday 02 March 1918, page 2.
Thanks to the government price controls I know exactly what strength this beer was. Between October 1917 and April 1918, beer that retailed for 5d a pint in the public bar had to be between 1036º and 1042º. After April 1918, that was knocked down to 1030º to 1034º.
That makes this a Government Ale. Not exactly the greatest hit with drinking punters. In most of the country it was a type of watered down Mild Ale which, as the war progressed, became more water than Mild.
They're taking a very upbeat approach to pushing this watery stuff. I guess they had no option. It's not as if breweries had much control over what they brewed, given the level of government interference in the industry.