Dave, thank you for your reply.
As stated in your statement, you never thought about tax because of fairly meagre royalties.. You can put this right.
My advice to you is that you should register for self-assessment. This would provide HMRC with the information they need to set up the right records for you.
You can register online for self-assessment and the link is
Please tick the box against "I have been getting untaxed income that cannot be collected through my PAYE tax code" and state the start date.
You will be issued with a Unique Tax reference number (10 digits e.g. 12345 67890) and you use this number to correspond with HMRC in future.
You will receive your UTR No and normally the first tax return for completion in the post.
In the meantime, prepare your accounts showing royalties income and associated costs. Please make a note of tax suffered at source if any.
You will then file a tax return and show royalties income (casual income) in the main section of your tax return in box 16 under the heading "Other UK income not included on supplementary pages. (tax return Page TR 3). Here is a link to the tax return. Form SA100
As far as rental income from inherited property is concerned, you should declare your share of this by completing supplementary pages SA105 – UK property of tax return.
I hope this is helpful and answers your question.
If you have any other questions, please ask me before you rate my service – I’ll be happy to respond.