Capital gains tax question on house I own

I bought a house in 2007 with my partner at the time. We split up in 2009 and he came off the mortgage and deeds. In order for me to keep the property I had to put my mum on the mortgage and deeds to meet the affordability calculator of the lender so that I didnt lose my house. No money was paid to or from my mum. I paid the deposit in 2007, solicitors fees, all mortgage payments and have continued to do s . My mum was just on there for affordability purposes only to meet the lenders criteria. She has her own home that she lives in since the 70s with no mortgage. I now want to refinance my mortgage, borrow some more , extend the term and take my mum off. She is happy to come off, sign the deed, expects no money , has had no benefit or made any payments. Does she have to pay capital gain tax even though she has never paid any money or gained anything. I cant seem to find the answer but would seem unfair if so as ive been paying the property all these years and so I'm hoping it's not the case. To confirm i will remain in the property and on the mortgage as i now meet affordability requirements with the lender. I don't own and have never owned any other property. My mum has never lived in my property and will gain no benefit. Thank you for your assistance.

Hi Nyk Myw,
She may be as she is been a a legal owner .
Please see here:
Capital Gains Tax: what you pay it on, rates and allowances
Thank you.