It's better to give than to receive, they say. Rubbish, I say.

My sister is a year older this week and, being the caring, thoughtful big brother that I am, I went out in search of something special for her.

Girls like perfume and shoes, right?

Perfume it is then, because I wouldn't know what size she takes in a shoe – and buying footwear for your sister seems kind of creepy if you ask me.

Unless I was buying her a pair of running shoes or something, which would only lead her to conclude that I think she needs to get more exercise. Definitely perfume.

So I look to our mother for some guidance on what kind of fragrance my sister likes.

"Just something for everyday use, something she can wear to work," mum says.

I wonder why she would need to smell different at work than she does on a night out, but think better of getting involved in a conversation that will only lead to further deliberation.

Off I toddle to a perfume shop in my lunch break and ask the nice lady if she can recommend something for my sister, who I inform her is in her late 20s and wants a perfume for everyday use.

Thankfully, the lady understands and starts to rhyme off a list of suitable products. Some seem to come with free gifts, which sounds good to me.

My sister is sporty, so the one with the free gym bag sounds pretty good. Until the lady tells me the price – I love my sister, but I'm not trying to buy her silence.

Hinting that we are some way off what we Lachs consider a spending limit for a birthday present, without looking like a tight git, we soon hit the correct price range. No free gifts mind you, but there is a special deal on one particular product. A 150ml bottle for half the usual price.

As the lady explains: "The 50ml bottle is £10 more expensive, so it really is a great deal."

A great deal it may be, but I have some anxiety over whether my sister will know I have bought the one on special offer. Perhaps paying more for the smaller bottle is the right thing to do?

The nice lady looks at me like I've just stepped off the 8.40 from Mars before suggesting I spend the £10 I will save on an extra wee gift.

Good thinking, madam, very good thinking indeed.

I leave the shop with a sense of great achievement – and promptly spend the £10 on snacks and fizzy juice to see me through a hard afternoon at work.

If my sister would rather have had shoes, there should be enough perfume in this big bottle to mask the smell of disappointment. Result!