Green’s Dictionary of Slang

1. (UK Und.) well-off.

1848

Flash Dict. in Sinks of London Laid Open 95: Above par, having the needful, possession of the poney, plenty of money, ‘best bliss of earth’.

2. in good spirits or health.

1885

Bulletin (Sydney) 2 May 24/1: For poet ne’er sung of the eye above par, / And its somnolent light when the lid is ajar, / Or the fruitful suggestiveness ever that lies, / Enshrined in the depths of a ‘pair of black eyes.’.

3. mildly drunk.

1934

Wodehouse Right Ho, Jeeves 196: ‘Mr Fink-Nottle is in a somewhat inflamed cerebral condition.’ ‘That’s true. A bit above par at the moment, as it were?’.