Final answer:
The texts provided do not directly answer the question, but they offer context about the UK's oil business and its importance in the mid-1980s. Additional specific research is needed to find the exact percentage of UK revenue from oil and gas in 1984-5.
Step-by-step explanation:
The question relates to the historical contribution of oil and gas to the United Kingdom's revenue during the fiscal year 1984-5. Although the provided texts do not directly specify the percentage of UK revenue from oil and gas in the year 1984-85, they give us insight into the importance of oil in the global and national economies. We learn about the discovery of oil in the North Sea about 50 years ago, which thrust the UK into the oil business, and how production followed the discovery, peaking in the 1970s, with most of the oil having been extracted since then.
By understanding the historical context, we can deduce the significant role oil played in the UK's economy during that era, though the texts suggest that by the mid-1980s the oil production was past its peak. However, to answer the student's question accurately, additional information or research would be required to find the exact percentage from that year.