[Read the whole of the 'Back-winter' scene here.]

My candidate for Backwinter is Sir Robert Cecil, younger son of Lord Burghley.

In 1592 Robert Cecil was 29. He was small, physically slight and had curvature of the spine. Intelligent and well-educated, he was being fast-tracked to political power by his father, who at 72 was England's senior statesman. For two years the pair had been grimly pursuing the key post of Secretary, left vacant by the death of Walsingham, but with her favourite Essex lobbying jealously for his own nominee Elizabeth postponed a clash by not formally appointing anyone. In the interim however she let Burghley take over the workload, and he was thus able to involve his son: 'Privately, Cecil was thrust forward, and to gain experience assisted his father and so had sight of many papers.' (Handover, p.73)

In May 1591 after an extended visit to Burghley's home in which entertainments reiterated her old councillor's need for help in his duties, Elizabeth knighted Cecil, and in August made him a Privy Councillor - an honour not yet extended to Essex. 'The appointment...made it possible for allow his son to handle the more secret state papers. When (Burghley)..was disabled by gout in October, Cecil was specifically charged with foreign affairs, and throughout the month dealt with them, prompted by notes from his father'.(Handover, p.79) He also bore responsibility for some home affairs. He had become de facto Secretary. It was clear to everybody that politically Cecil was his father's heir.

Winter's younger son is called Back-winter

Having interviewed and rebuked his elder brother, Summer bids the younger to come forward:'Back-winter, stand forth.' Vertumnus needlessly scolds: 'Stand forth, stand forth; hold up your head, speak out'

Burghley's younger son was a hunchback.

A diminutive figure, he was physically incapable of standing upright and with head erect. You would expect his enemies to dwell on this, and they did:' was an unwholesome thing to meet a man in the morning which hath a wry neck, a crooked back or a splay foot'. His nicknames - Monsieur Bossu, St. Gobbo, Bossive Robin, the Toad - harped on it through life.
Back-winter is Winter's favourite, the son for whose advantage he schemes:
'All for a fowle Back-winter he layes vp;'
'Back-winter...thats his none sweet boy
Who like his father taketh in all points'
Burghley was clearly grooming his younger son, who alone had inherited his intelligence:'There can be no doubt that his father intended him as his political heir.' (Handover,p.34)
Back-winter is a monster of malevolence, anxious for power so that he can oppress a world he hates:
'An elf it is, compact of enuious pride
A miscreant, born for a plague to men
A monster..."

'Spirits, come up: 'tis I that knock for you
One that envies the world far more than you.

This is not how Robert Cecil's complex psychology strikes us today, but his political enemies may have chosen to believe something like it. The essay by his cousin, Francis Bacon, On Deformitie, makes a direct link between physical disability and inward malice:'Deformed Persons are commonly euen with Nature: For as Nature hath done ill by them; So doe they by Nature: Being for the most part, (as the Scripture saith) void of Naturall Affection...' Published shortly after Cecil died, this essay was understood at the time as a reflection on his character.
Summer's verdict on Back-winter is:
'Winter, imprison him in thy darke Cell,
Or, with the windes, in bellowing caues of brasse,
Ne're to peepe foorth, but when thou, faint and weake,
Want'st him to ayde thee in thy regiment
"In a letter to Hatton after Cecil's promotion to the Privy Council, Burghley termed (his son) 'a vicar her(e) servyng as a curat under me. He is as yet hable for no gretar cure, but I hope he will in that behalf dischardge me of my cure' (BL, Cotton MS Titus C VII, fol. 16r)" (Hammer, p.100, note)
Back-winter is represented as snarling, surly, rude and out-of-control - more like a malign toddler in a tantrum than a statesman. He behaves like a devil in a medieval morality, throwing himself down and biting the ground. This hardly fits the real Cecil, who seems to have been generally courteous and formidably self-controlled. Perhaps that was why it was funny?