Getting taxed for the first time query

[Johnnyren]

Hi
I have a tax issue will try to keep it as simple as possible

I have semi retired and am recieving 1400 pounds per month from my 25 % tax free alllwance

I have had a part time cleaning job for 2 years paying 110
A month

Recently the company was taken over and the wages went to monthly I was being paid 220 a month still paying no tax

Last week the company went finally to monthly pay and I paid 70 pounds in tax and I notice my tax code changed
Is there a reason for this ? Have I went over a threshold , Why for the previous 2 years hadn’t I paid tax , Any help appreciated