You asked

What were the number of company bankruptcies and start-up failures, expressed as a time series?

We said

Thank you for your recent enquiry.

Unfortunately we do not hold the information necessary to fulfil your request. For information on company bankruptcies, your request may be better placed with The Insolvency Service. They may also be able to assist with your query on company start-up failure, but you may also wish to send your query to The Department for Business, Innovation, Energy and Skills.

Although it does not answer your query, you may find tabs 4 and 5 in the following link of interest;

https://www.ons.gov.uk/businessindustryandtrade/business/activitysizeandlocation/bulletins/businessdemography/2016