Before revision:  The paper presents a simple mathematical model of the process  and uses well-known results from control theory to prove that the approach taken by China and, to a slightly lesser extent, by Italy can work if the effect of delays is accounted for when taking the decision of the country lockdown, while the approach currently announced in the UK is likely to fail.
After revision:  The paper presents a simple mathematical model of the process and uses well-known results from control theory to prove that suppression strategies based on daily test reports can be effective if enacted very early, while mitigation strategies, including trying to achieve herd immunity, are likely to fail.