It is not every day that the Head Girl and her dorm mate turn up at your study and ask you to lift your skirt and 'spread 'em.' which means there is no set rule of etiquette for such an occasion. At such moments, one relies on common sense and good manners. A lady should not expose her underwear in public knowingly, so accordingly I invited them inside.

'Hi Mel,' said the Head Girl to our lovely Rhodes Scholar, Melissa Dee, 'you are welcome to stay while we examine the state of Hoffy's knickers, or panties as you would say in the US of A.'

'I am Canadian, as a matter of fact,' said Mellisa, 'and as I was invited into Miss Hoffmann's rooms, I shall stay until asked to leave by my hostess. I thought you English were hot on etiquette?'

Rebecca's eyes narrowed.

'Sarah,' she said, turning to her delicious room-mate, the always happy Australian scholar, 'camera phone to the ready.'

'Oh, and I ought to remind you, Head Girl, that there was nothing in the agreement about anyone "spreading 'em," after all, how would you like it if Miss Susie made you do it?'

To judge by the colour Rebecca turned, Mel must have said something relevant, though for the life of me I could not think what.

'It's a lie, I tell you, a damnable lie. I got the Head Girl's job on merit not because I was fucking Miss Susie! Oh fuck.'

With that cryptic comment, she turned to me.

'Okay Hoffy, skirt up!'

I looked at Mel, who was smiling, encouraging me; what a darling she was.

Slowly, I raised my skirt, first revealing the tops of my stockings and the pink suspenders, and then, as it reached my hips, my white cotton knickers -- regulation style.

'Snap them, Sarah. Turn Hoffy, let Sarah get a good picture.'

I did as I was told.

Mel's nice smile helped me to bear it.

Sarah was blushing, but took the snap all the same.

'Good girl Hoffy, but are they cotton? I think I should feel.'

I hesitated. Mel looked at me and nodded, which helped a lot.

Rebecca rubbed her finger along the line of my slit, pushing my knickers in a little.

'Well, they are cotton, but Hoffy, they are also wet. Why would that be? Yes, definitely moist Hoffy. Don't say that having the Head Girl examine your knickers is getting you off?'

I blushed. Mel came to the rescue, bless her.

'Well, Rebecca, Hoffy having carried out her half of the deal, I suggest you do the same. Lift and show us.'

Mel had what is called, I believe, a 'shit-eating grin,' on her face.

Sarah looked shocked.

'You can't expect Becca to show you her panties, that's not right.'

'Actually, Sarah, that is the deal. Miss Hoffmann sets a good example, and in return for not examining all the girls, Miss Susie or Pix or one of the other teachers can examine Becca's knickers. Up with that school skirt, Becca, and let's see if the undies are regulation. I have my phone camera to record it.'

'Hoffy!'

Rebecca narrowed her eyes. Was that the trace of a pout I saw?

'Rebecca, that was the deal, so I am afraid you have to show.'

I was only, as I told her, telling her what was in the agreement.

Blushing furiously, she lifted her skirt. Those legs were wonderful. My eyes travelled up them, as did those of Sarah and Mel.

'Miss Hoffmann, darling,' said Mel, 'correct me if I am wrong, but is a black lace thong regulation school underwear?'

Sarah was blushing too, and I was not surprised, those were seriously sexy knickers. Good job my own were not being examined after I saw those, I thought.

'It's not fair Miss, I am going off to see my boyfriend this weekend, and he, well he likes...'

Her voice trailed off.

'Well, Becca, let's at least check if they are cotton,' said Mel, smiling.

'Well they obviously aren't, you nitwit,' said Rebecca.

'That,' smiled Mel, 'is for Miss Hoffmann to decide. Miss H, do reciprocate Becca's care and attention.'

Well, what else could I do? It was in the agreement we had reached, and oh my goodness, I did want to, well, feel what Rebecca's knickers were made of. My guess was silk; I was correct.

Rebecca looked even sexier than usual when she blushed.

The problem with a thong, as opposed to regulation school knickers, was that where the latter had an actual gusset which could be touched without there being any contact with the moist lips themselves, thongs tended to disappear between the lips, which meant that I could not avoid contact with Rebecca's cunt.

She wriggled most becomingly as I curled a finger in, hooking her wet gusset into my fingers.

'Becca,' said Mel with a smile, 'don't say you get off on showing your panties to the Deputy Head and Sarah and I?'

'Oh, fuck,' said Rebecca, giving a little moan as my knuckle inadvertently grazed her clitoris, 'oh bloody bugger.'

As she never, ever used bad language, there was a special frisson in hearing her swear. We always taught girls that language should be used carefully, especially the bad sort and, as usual, Rebecca led the way.

Sarah was chewing her nails, looking very anxious as her room-mate started breathing heavily.

Mel, on the other hand, was staring intently at what Becca was revealing.

'Well, Miss, you'd have to admit that her boyfriend will be in for a treat, she's a sexy kitten, that's for sure.'

'Oh fuck!'

Poor Rebecca, she seemed quite discomposed.

I thought it time to put an end to the poor girl's ordeal, and withdrew my finger from the gusset, but, instinctively, as with Miss Susie, I licked my finger. Gosh, she tasted almost sweet. Rebecca trembled and let out a delightful little moan.

Mel spoke up.

'Sarah, will you check on Miss Hoffmann's cunt?'

Sarah blushed and refused.

'Oh well, I shall do it myself.'

She fingered the camel toe of my panties, looking at Rebecca as she did so.

Somehow my fingers were not moving.

'Ladies, I think we have a problem here. You are both gagging for an orgasm, and it would be unwise to let you both leave in this state. Sarah, pull down Becca's panties, I will pull down Miss Hoffmann's.'

Rebecca blushed as she looked at me, and I did the same, looking back at her plaintive eyes..

I felt the cool air on my ass and cunt as my sticky panties were peeled away from my gooey slit. I could see the girl goo on Rebecca's as Sarah pulled them off, a task at which she appeared to have some skill.

'Legs open, ladies,' Mel ordered.

Rebecca and I complied.

We looked, blushing at each other as she touched our cunts.

I moaned as her finger located my aching clit. So did Rebecca.

'Kiss,' she ordered.

We shuffled closer, the tall Rebecca bending to be able to reach my lips.

As we kissed, our tongues entwining, I felt Mel's skilled hand play with my cunt, fingers curling into me, her thumb strumming my aching clit. From the look of her, Rebecca was undergoing the same treatment. Sarah seemed transfixed, as though she wanted the it but did not dare ask.

Mel clearly knew her way around the female genitalia, and could multi-task, as she seemed to be able to keep Rebecca and me on edge simultaneously. Seeing her face suffuse with redness as Mel skilfully played on her clit while finger fucking was erotic by itself, to watch it whilst I was going through the same experience, brought it to a new level; add to that the fact we were kissing and holding each other, and being watched, it was no surprise that we reached the edge rather quickly. But Mel kept us there, taking us almost to the point of no return, and then stopping.

'Beg for it, sluts!'

Rebecca blushed.

'Oh fuck, yes, yes, please Miss Mel, my cunt needs to cum!'

I felt myself blushing furiously.

'Oh gosh, Miss Mel, please, pretty please can I cum, please!'

Mel smiled.

'No, edge some more, sluts!'

Rebecca and I looked at each other in deep empathy.

'Please,' I said, can your two sluts come, Mistress Mel?'

'Pretty please,' added Rebecca.

With a grin, Mel graciously granted our petition.

'Cum, sluts!'

Rebecca tasted delicious, and we kissed and clung on to each other for fear of falling.

She broke off:

'Oh fuck!'

She began to gasp.

That set me off.

'Oh my goodness!'

As our legs buckled, we clung all the more tightly to each other.

Rebecca started to orgasm, which, again, set me off.

Mel's skilled fingers, combined with the sheer erotic charge of what we were doing, caused us both to climax under her demanding fingers.

Rebecca and I fell into each other's arms, kissing, and falling back on my sofa -- spent.

'Now, Sarah, clean Becca up.'

Sarah looked spooked, but did as Mel ordered, applying her tongue to Becca's thighs and her lips. Becca came again, which meant Sarah had to repeat the operation.

'I had best clean you up, Miss Hoffmann,' smiled Mel. The feel of her skilled tongue on my thighs made me tingle. I did not orgasm a second time, but finished feeling delightfully relaxed.

Taking a few moments to recover, Rebecca adjusted her clothing, kissed Sarah and thanked Mel.

'And Hoffy, that was delicious', she smiled, 'I shall think about it next time I, well next time.'

I blushed.

'You are delightful my dear, so utterly yummy.'

'Can I have my thong, Mel?'

'Not to wear, that would be quite wrong, but do put it in your handbag and wear Miss Hoffmann's panties back to the Dorm.'

I wanted to protest, but Mel stopped me.

Rebecca slipped on my wet panties.

'Well, now you are wearing regulation panties, Becca. We shall require proof, so pose.'

Of course, as I was so tiny my panties were rather stretched on Rebecca, but there was now photographic evidence that, as promised, the Head Girl and the Deputy Head had both fulfilled their sides of the bargain. Hurrah St Trinian's, we declared.

A little later my WhatsApp pinged. There was a photograph of my panties on the wall of the sixth-form Common Room, with a note from Rebecca:

'You're a star, Hoffy!'

Oddly, that was what Mel had said only a quarter of an hour ago when I made her orgasm for the third time. Sometimes my job is the most satisfying one in the world.