Note 27 - Share-Based Payment and Equity Settled Share Option Schemes - Assumptions (Details) - GBP (£)	12 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Statement Line Items [Line Items]
Weighted average share price (in pound sterling)	£ 3.72	£ 2.50	£ 2.70
Weighted average exercise price (in pound sterling)	£ 2.66	£ 0.70	£ 1
Expected life (in years)	7	8
Bottom of range [member]
Statement Line Items [Line Items]
Expected volatility	32.00%	39.00%	51.00%
Expected life (in years)	6	6	6
Risk free rate	2.19%	1.57%	2.17%
Top of range [member]
Statement Line Items [Line Items]
Expected volatility	57.00%	74.00%	85.00%
Expected life (in years)	10	10	10
Risk free rate	2.36%	2.41%	2.37%

The expected volatility of the share price used to calculate the fair value of the share options granted. Expected volatility is a measure of the amount by which a price is expected to fluctuate during a period. The measure of volatility used in option pricing models is the annualised standard deviation of the continuously compounded rates of return on the share over a period of time.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2017-01-01
-Paragraph 47
-Subparagraph a
-Clause i
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-URIDate 2017-03-09

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The option life of share options granted.

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The implied yield currently available on zero-coupon government issues of the country in whose currency the exercise price for share options granted is expressed, with a remaining term equal to the expected term of the option being valued (based on the option's remaining contractual life and taking into account the effects of expected early exercise). [Refer: Government [member]]

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The exercise price of share options granted.

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The weighted average share price used as input to the option pricing model to calculate the fair value of share options granted. [Refer: Option pricing model [member]; Weighted average [member]]

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