It had been two days since Matthew Sinclair had taken his mother-in-law, Elizabeth St John, to great sexual heights by doing all sorts of things to her large backside at her request and both parties were wanting more. Elizabeth had said that she wanted a spanking and a fucking next time and Matthew fully intended to give her both of those things.

It was important, of course, that Matthew's wife Kate did not know what her husband and her mother had been up to and intended to be up to, so they had to try to make things appear as normal as possible.

Before the ass worship session, the relationship between the two had been cordial without being particularly close but with Matthew now having had his face deep into Elizabeth's arse crack, things could never be quite the same again.

Matthew had never been in the habit of calling on Elizabeth and her frequently absent husband Stanley unannounced, so they had to keep that the same. There had also rarely been direct telephone contact between the two as usually requests for Matthew to do something or other for his in-laws normally came via Kate, so that too needed to continue so as not to raise any suspicions.

Elizabeth phoned her daughter's mobile. "Hello, Kate, Matthew had one more little job to do for me, do you think you could spare him for a couple of hours soon, please?" she asked.

Despite the efforts of Elizabeth and Matthew to hide things, Kate had noticed a change of some sort in her husband in very recent times although she had no idea what had caused it. Kate and Matthew had actually had a couple of minor arguments, so Kate grumpily snapped back at her mother, "You can have him for longer than two hours as far as I am concerned."

Although extra time with Matthew was very appealing, Elizabeth thought she should delve deeper. "Oh dear, darling, is something wrong?" she asked.

"Nothing major but he is being a bit strange, that is all," replied Kate.

"Do you want me to have a word with him when I see him?" asked Elizabeth with fake concern.

"No, no need, we are just going through a little difficult patch at the moment. I will tell him that you need him," said Kate.

Elizabeth thought to herself, 'Fuck yes, I need him' but just responded to her daughter, "Thank you, darling."

Later Kate said to Matthew, "Mum says that you still have one more job to do for her, I suppose you know what she means."

"Yes, there was something else that she wanted seeing to," replied Matthew and was elated because he would be seeing Elizabeth again soon and would be both spanking her and fucking her.

Matthew thought that he had better not appear too eager, for Kate's benefit, because that would have been out of character, so he asked Kate to tell her mother that he would go to her house the next day.

Both Matthew and Elizabeth had been counting the hours but when Matthew arrived at Elizabeth's house, with Stanley again being out, they had a long kiss and Matthew put his hands on Elizabeth's large backside, which was, for the moment, inside trousers.

As they made their way to the bedroom, Elizabeth said, "I want a really hard spanking, you know."

"That is exactly what you will get, you sexy slut," replied Matthew.

Once in the bedroom, there was a bit of debate as to whether Matthew would be better with his clothing on or off, but they settled on the removal of his trousers and he kept his underpants on with his now solid penis inside. Elizabeth, of course, would not be wearing any clothing down below but she initially removed her blouse and bra and her impressive tits were on display as she stood to the seated Matthew's right-hand side.

Matthew dragged her trousers down and then her knickers and she stepped out of them. "Over my knee, young lady," he instructed and they both felt a sexual surge at those words. The naked Elizabeth positioned herself over her son-in-law's lap and his erection pushed into her body.

Matthew ran his right hand over her buttocks before going straight into the spanking: SLAP! SLAP! SLAP! SLAP! his hand hit Elizabeth's cheeks and Matthew very soon got into a rhythm of steadily spanking from one buttock to the other.

Elizabeth had had very few spankings in her sixty-three years but her son-in-law was certainly giving her one now as his slaps got harder and faster and were no longer on alternate cheeks but sometimes there were several on one spot.

Elizabeth wriggled and bucked and 'Owwed' and 'Ooohed' but she was finding it hugely stimulating as her arse got hotter and hotter. "Harder," she ordered and Matthew very happily complied and spanked this sexy mature woman's backside as hard as he possibly could.

Although she was enjoying it, she was now really feeling it and she felt as though her arse was on fire as still, Matthew's hand made stinging contact with Elizabeth's buttocks. The noises that Elizabeth was now making were indecipherable but they were a mixture of pain and pleasure and Matthew had to grab her tightly with his left arm to stop her twisting off his lap.

Matthew's underpants were wet with his precum as he continued to spank Elizabeth's delectable arse but with every centimetre of her large backside now bright red, he decided to stop. Elizabeth was panting and sobbing and lying limply over her punisher's lap and Matthew was out of breath.

"Get up if you want to," he said softly and after a brief delay, Elizabeth struggled up and clutched her arse cheeks; her cunt had obviously been leaking because both her thighs and Matthew's thighs were sticky.

Elizabeth rubbed her bottom and, very red-faced, she looked at Matthew in almost bewilderment.

"You asked for a really hard spanking," he said as a sort of explanation.

"Yes, I did, didn't I?" Elizabeth sobbingly acknowledged.

Matthew was more than ready to fuck her now but he thought that he would wait until Elizabeth let it be known that she was too, which she promptly did by saying, "Please fuck me now."

Matthew was very happy to comply and he stood up and removed his underpants and also his upper clothing before he and Elizabeth met in a kiss. Elizabeth put her burning bottom on the bed and reacted with an "Ooooh" before she got herself a bit more comfortable and lay back and spread her legs.

Matthew got on the bed between her legs and had his erection brushing Elizabeth's cunt and he gently eased in as her vagina took the first genuine penis, rather than a dildo, that it had admitted in quite some time. Matthew was not huge but he was big enough, and once Elizabeth had got used to the penetration she said, "Mmmm, that feels so good."

They made slight adjustments to their positions as Matthew slid deeper in and then Elizabeth said, "Fuck me hard, Matthew, give me a good fucking."

Matthew had gone along with each of his mother-in-law's requests over the last few days and he proceeded to go along with this one as he built up a rhythm as he plunged in and out and had Elizabeth gasping and groaning. They were both highly aroused and Elizabeth knew that her first cock induced orgasm in years would arrive very soon as Matthew panted as he fucked her hard and fast.

"Yes, yes, oh hell, fuck, fuck," panted Elizabeth as her son-in-law took her to orgasm and Matthew continued ramming her.

The fucking went on and Elizabeth came again but Matthew knew that he was getting close. "Do you want me to cum in you?" he blurted out.

"Oh yes, I want your spunk, my horny stud," replied Elizabeth, although Matthew had never considered himself to be a stud, something that his wife would probably confirm. Nevertheless, he did as instructed and he ejaculated into Elizabeth as she again climaxed.

Matthew had now completed both tasks, a good spanking and a good fucking, and the two of them came down from their fuck in each other's arms. They had a shower, after Elizabeth had examined her glowing buttocks in a mirror, and kissed some more before Matthew got dressed. They did not want to push their luck by overdoing the amount of time that they spent together but they certainly intended to have many more sexual episodes.

When Matthew got home, feeling guilty but hoping that he was not showing it, Kate said, "Did you get that job done for mother?"

"Yes, I think that she was satisfied," replied Matthew, both pleased with his answer and the knowledge that he had very obviously sexually pleasured his mother-in-law.

Matthew was now to await a message from Elizabeth via his wife asking him if he could call around and Elizabeth had to decide when to make that request. Although they both wanted it to be 'the sooner the better' they both knew that they could not suddenly start spending more and more time together without raising suspicion.

With sex between Matthew and his wife next to non-existent at the moment and sex between Elizabeth and Stanley just a distant memory, Matthew relieved himself thinking of Elizabeth's arse and Elizabeth renamed her dildo, Matthew.

Both Matthew and Elizabeth were looking forward to the next time that Matthew paid attention to his mother-in-law's buttocks in one way or another.