easier to get mortgage if existing mortgage?

Thinking about paying off the last 20K of my tracker mortgage but wondering whether having an existing mortgage would be any advantage in getting a new mortgage in a year or so. Family has grown in size so likely that I will need to trade up to a bigger house. For example, from the point of view of getting mortgage approval, is it better to have a deposit which is 20K larger against a new property?

Maybe I should 'reduce' but not 'clear' the mortgage?

I'm aware of the issues around tracker vs deposit.

From speaking with a couple of banks lately they all seem to want a deposit more so than the current mortgage paid down. Which was a bit of a surprise as I was overpaying my mortgage. I've stopped this now and am putting money into saving for a deposit.

Hard to say, it probably differs from bank to bank. I see a couple of relevant and maybe conflicting points.
- Having a mortgage will mean you have monthly repayments. That leaves less disposable income per month to pay your new mortgage. That will count against you.
- Clearing it increases your disposable income, but reduces your deposit.

For the banks it'll come down to the size of your deposit and your disposable income.
- How much would your deposit be, percentage wise, if you clear/don't clear the mortgage?
- How much disposable income would you have after paying your mortgage if you clear/don't clear it?