Ok, on here we're all pretty laid back about sex, and probably aren't representative of the world at large. Even so I was shocked at some of the responses to this query about anal sex on Mumsnet
There seem to be a phenomenal number of people who seem to think that any man asking any woman for anal sex is somehow a foul pervert who should be told to get lost instantly. I think it's pretty offensive to think that. How else does anyone ever find out what a new partner might or might not like? Or in fact, what they might learn to like.
I love bum sex- both being pegged and hhaving my OH's arse: if I'd never asked, we'd both be missing out.
Unfortunately, a large percentage of the population still see anal play/sex as "dirty" and taboo. You can't force people to change their minds on something or be less judging of others preferences, but you can educate as to why it can be a fun thing.
I agree with Nat, a lot of those opinions are at least uninformed, and possibly malinformed, people who don't know what they're actually talking about sticking their tuppenworth in
I'd be more shocked if you linked me a mumsnet query that wasn't full of judgemental responses and crap knee jerk 'advice'! Awful site in that respect.
It would take me a while to be comfortable having anal sex with a new partner, but I wouldn't tell him to get lost or consider him a pervert. No matter whose bum we're talking about sticking things up. It's great to be open about sexual desires and really not ok to make someone feel they're dirty about theirs by calling them names or telling them to get lost (how juvenille!)- as long as no one is forcing things onto their partner that they don't want to do then what's the problem talking about or asking for new things. Give it a go if it sounds interesting and politely decline if not, right? If you're having sex, be mature enough to talk about sexual things with a bit of sense. But then, I'm probably not a good example since my problem would lie more in finding a partner kinky enough for me than being put off by one who is too kinky! :p
It just proves what a terrific bunch of people there are on here. Most of us have different tastes and not judgemental. As long as its legal and consensual adults are involved then anything goes.
Eww, that's gross! Disgusting, foul, vile, deviant pervert who obviously watches porn 24/7 and probably masturbates into chicken kievs whilst eating shards of broken glass! /endsarcasm
On a slightly more serious note, that thread made me want to round up a lot of these posters, stick them in a classroom and educate them a little.
I've had more partners who like (or love!) anal than ones that didn't. I've even had three who asked for anal! I had one GF who had previously had a bad experience with anal, but was willing to try it again with me as I'm a more gentle individual generally. And she loved it!
As for the OPs OH obviously being into porn - what utter crap. I first tried anal when I was 17, both on my GF at the time and her on me, before I'd ever seen porn. This was in the days pre-internet. *shows age* 
Oh well. At least we're a more enlightened and non-judgemental bunch here on the LH forums! 
I agree with Nat, a lot of those opinions are at least uninformed, and possibly malinformed, people who don't know what they're actually talking about sticking their tuppenworth in
Misinformed I think is the word.
Maybe the problem is that they haven't been sticking their tuppenworth in?  *looks smug for using a phrase to refer to anal sex which previously had nothing to do with it*
Going to take a different stance here and say I think they seem to feel it's inappropriate for a new partner to ask, especially in light of OP's previous experience with it and her not wanting to do it. Not purely an 'OMG anal sex ew' reponse. OP said: I want to please him but at the same time don't want to go along with something I'm not sure I want to do.
I would have told her to say no as well, since she's already clearly pointed out that she's not interested in it. And if he's a good partner, he won't insist on it. I don't think any of the responses labelled the new partner as a "foul pervert" just because he brought up anal. Also it's fair to bear in mind that despite many folk on this forum being more adventurous, anal sex can and is painful and unpleasurable for many people out there. And if people aren't comfortable with it, I personally see no need to try and convince them.
Going to take a different stance here and say I think they seem to feel it's inappropriate for a new partner to ask, especially in light of OP's previous experience with it and her not wanting to do it. Not purely an 'OMG anal sex ew' reponse. OP said: I want to please him but at the same time don't want to go along with something I'm not sure I want to do.
I would have told her to say no as well, since she's already clearly pointed out that she's not interested in it. And if he's a good partner, he won't insist on it. I don't think any of the responses labelled the new partner as a "foul pervert" just because he brought up anal. Also it's fair to bear in mind that despite many folk on this forum being more adventurous, anal sex can and is painful and unpleasurable for many people out there. And if people aren't comfortable with it, I personally see no need to try and convince them.
I think perhaps one issue was the short initial post from the OP. I don't recall her mentioning how new her partner is, which is something which is subjective too. If they've been one one date, then it's too soon I think. If they've been dating for 6 months, then I think that's a reasonable time. I suppose him asking is the only way he can find out. At least he asked I guess! Better than "Whoops, sorry!"
My "foul pervert" comment was just my sarcasm and hyperbole. Some responses were so extreme (including someone telling her to dump him!) that I thought I'd poke fun at the general negativity of a lot of the responses. I know here we'd be more level-headed and respectful to the OP. 
If he does insist or keeps pestering than it should definitely be a case of "there's the door, please use it."
If anal sex is important to any partner, surely it is worth putting it on the table fairly early on (maybe not first date or hook-up etc but before a relationship gets serious). If the woman told her partner early on that she wanted to be whipped and spanked after reading 50 Shades would it be right to condemn her for being 'too pushy' etc...? Or is she just being empowered? Should the man let his partner down a year or two down the line when a relationship has already been invested into? Who's the bad guy/girl and when?
If anal sex is important to any partner, surely it is worth putting it on the table fairly early on (maybe not first date or hook-up etc but before a relationship gets serious). If the woman told her partner early on that she wanted to be whipped and spanked after reading 50 Shades would it be right to condemn her for being 'too pushy' etc...? Or is she just being empowered? Should the man let his partner down a year or two down the line when a relationship has already been invested into? Who's the bad guy/girl and when?
If I'm honest these groups often don't allow openness, even in local mumnet style groups I've experience lack of support and understanding when I need to have my OH to attend events due to my spine. Often it's either he's a pervert or th other women need a safe place with no men :-/
I think it all depends on the person I don't think its taboo but can be fun if done right. Some don't like the idea while other love it. It all depends on the person that you are going to have sex with.
Gotta say though, those parenting forums are the worst. I asked a question about developmental milestones on Mumsnet once and got so many nasty comments back, because people assumed I was trying to force my baby to grow up and do things he wasn't ready for, they even accused me of not loving him as he is, when literally all I said was "he's not doing xyz yet, should I be concerned?" 🙄 I'm a regular on Netmums too and there's a lot of god awful judgemental people on there as well, but it's not quite as bad as Mumsnet, I'll never use that site again!
With regards to your original question, if anal is something you absolutely don't want to do, then just politely let him know that. It's better that he's aware of it now, rather than secretly hoping he can convince you further down the line, only to be disappointed. It's okay to have hard limits, and I'm sure if he likes you then he will respect that.
However, it sounds as though your previous experience with anal wasn't done 'properly', as for most people it requires a lot of warm up, trust, and willingness. It could be worth looking in to it and perhaps trying some small anal toys, but only if you want to, not just to please someone else.
P.S. We tried anal twice, with plenty of warm up so it didn't hurt, but I just didn't like sensation of feeling like I needed a massive crap the whole time 🙊 So I don't get what all the fuss is about with anal personally, and I don't see how it can be pleasurable (but that's just me). I told my OH I wouldn't like to try it again and he was completely fine with that, and has never brought it up since. I don't think he was that fussed anyway though, and he certainly wouldn't let me peg him so he wouldn't expect it from me.