Was I wrong to buy the chairs without husband?

What a selfish arsehole he is, OP. He's also disrespectful to/about you in front of your children and has trained you so that you have to check with others whether he's being unreasonable or not...I think all of this is worthy of a bigger discussion than what you spend your £80 birthday money on. (It should go without saying but no, you were not wrong to buy the chairs without asking your husband's permission.) Nip that shit about bad mouthing you to the children in the bud. He's training them to have no respect for you and think it's acceptable for partners to call each other stupid and dismiss each other's needs.

£40 the pair? Bargain, no wonder you snapped them up. He can sit on one of the old chairs then.

If your parents had gifted you the chairs directly, would he have complained? You can use your birthday money as you wish!

I'd just reply that I bought what I wanted with my money so he can just fuck off and mind his own business.

Let him sit on the grass if it bothers him that much, what a tosser, telling you how to spend YOUR birthday money. I would have laughed when he said that and said "Yeah right, I know you're joking but it is my birthday money" Makes him look a bigger twat to say " But I wasn't"
You and the kids enjoy your chairs OP.

Yep. He's a dick.

How expensive were these fancy chairs that he thinks they were a waste of money and you think you should’ve consulted him about spending your own money? Is he usually a grumpy git?

My God, I’ve painted entire rooms and brought all sorts of things for the walls plus bought and built 3 chairs without consulting my DH. He couldn’t care less.

Please ensure he knows he is not allowed to sit on the new chairs.

I’d make satisfied, gleeful noises every time I sat in one.

Maybe throw in a “I’m so happy with my new chairs” every so often, too.

Who was sitting on the shit chair?

Unless you have an urgent debt problem or can't afford the basics and that money could have helped then yanbu. It was a present. Presents are supposed to be things we want rather than need. A treat rather than a necessity. Otherwise people would get each other basic groceries or replace a broken item for their birthday. How would like it if you allocated his birthday money for something the family needed, like a lawn mower spare part or towards rhe council tax. I'm assuming they gave you money so that you could get something you fancied. Unless your finances are really struggling, he is being mean. You could offer to return one of them if he agrees to always sit in the shitty chair, since he doesn't need a nice one

He's being a miserable prick. Remove his chair and enjoy garden time without him.

If your parents had asked you what you wanted for your birthday and you’d said “two lovely garden chairs, let me send you a link” and they had bought them and given them to you, he couldn’t have said you were wasting money because they were a gift. Or if your parents had noticed you only had three nice chairs and just bought two more nice ones. This is exactly the same. Your parents gave you money to buy something you wanted and would get joy from, not for the money to get lost in buying groceries or general household spending.

Tell him that’s fine, he can sit on an old chair, you the kids and a guest can use the new ones, and that if you ever catch him on one of the good chairs, there will be hell to pay

and then remind him ever time. Why are you sitting on the stupid chair, sit on other old chair, remember you felt they were fine.

He's being a prick!
You can do what you want with your birthday money. It was kind of you to spend it on something that's nice for the family.
Tell him you had better not see him sat on the nice chairs as he thinks they are such a stupid buy.

My husband claims he does not want to be involved in any home furnishing decisions. I never spend much money on our home as I’m very frugal in that regard. No matter what changes I make, even if they are replacements for broken necessities, he complains.

the reality is he just doesn’t like change.

Does your husband have similar issues?

Your birthday money your decision.

I’ve I was feeling particularly miffed, I might put one of the nice chairs away and leave one of the old ones out especially for him as he prefers those.

I mean it was your birthday money, so in theory it's up to you how you spend it. However, if finances are super tight, and it's the difference between paying rent or not, then he might have a point. Otherwise, it's your money and a couple of poxy chairs. No need for the drama.

No, of course not. They're just chairs, FFS.

Tell him to think himself lucky because you were thinking of spending the money on male escorts and cocaine and decided on the chairs instead.

He's a prick.

Have yourself a birthday drink on your new chairs and tell him he's not invited.

They’re YOUR birthday chairs bought with YOUR birthday money. You could have spent it on vodka and Marlboro Lights if you wanted. Don’t let him sit on the new ones and tell him not to be such a controlling prat.

This surely can’t be the first time he’s been like this over a purchase or money in general?