You could very easily walk past it without realising it is there, writes Katie French. 

And it is what makes Cecily Spa on Windsor High Street such a unique, hidden gem.

But once you realise what lies behind the pretty pink door, you’ll want to return as it is a lovely little high-end Oasis and feels a world away from the bustling streets below.

Cecily Spa is one of three boutique spas in the UK and its Windsor branch has only been open since June. The Observer was invited along to visit for a treatment over the summer.

The spa itself is tucked away on the top floor of a high street building through a doorway adorned with flowers and up three flights of stairs.

As someone who was there for a pregnancy massage, I’ll admit I needed to pause for breath on a couple of occasions!

But the views when reaching the top floor were well worth the climb. Overlooking Windsor Castle and almost at level with some of the grand building’s windows, I half wondered if you'd be able to see King Charles eating his morning boiled egg.

The interior of the spa is just as impressive as the view. The furnishings are sumptuous and plush, giving a high-end vibe. And the fact that it is only accessible via private appointment adds to the air of exclusivity. The business is hoping to attract small groups - friends, mums, hen parties etc. They also have an apartment on the floor below where guests can book to stay in combination with the spa visit - a great idea for a bridal party or celebrating a special occasion.

During my visit I was treated to an hour-long relaxation treatment designed to bring comfort to women in either the second or third trimester.

The massage was divine - perfect for aching limbs. As a working mum, I find it hard to switch off so was grateful for the ear plugs and eye mask which helped me switch off and relax.

The treatment took place behind a thick curtain. As the spa is designed for exclusive use, this felt private enough however if it was open to members of the public or if the spa was super busy, I could imagine one might feel a little more exposed.

I came away feeling incredibly relaxed. It was a lovely luxury that every expecting mother should be afforded. This wold be a great present for a friend, colleague or loved one.

Cecily Spa is a boutique chain of spas, with three award-winning outlets in Berkhamsted, Marlow and now Windsor.

The chief executive and founder is Haylee Benton, a salon entrepreneur and investor, who also owns Alchemy & I Hair Salons in the UK and New Zealand.

Cecily Spa in Windsor is now accepting bookings. For more information, visit www.cecilywindsor.com.