Okay I'm not a parent myself but I do a lot of cooking for my Nephews, Nieces and Godkids so I'm always checking various Websites for foodie stuff.
For those that are interested, the lowdown on Chesswood Creamed Mushrooms is yes they are still available but in a new form.
A few years ago Malton Foods (not surprisingly based in Malton, Yorkshire) moved out of the canned goods market and at that time ceased production of Chesswood Creamed Mushrooms.
However, due to popular demand, they relaunched them in microwaveable pots.
The tinned versions by then had disappeared from the high-street shelves of the likes of Tesco's and Sainsbury's and sadly these stores to my knowledge have not picked up the new microwaveable line.
I have seen them available in Nisa stores (which are quite prevalent near me in the North West) but not sure about stores in other parts of the country.
The RRP of Chesswood Creamed Mushrooms in the microwaveable pots is about £1.29 per 200g pot which is a bit more expensive that what we used to pay for the 230g tin (plus you get a little bit less).
I find them just as tasty as the original (although they don't look as appetising in the pot before you microwave it).
You can also buy them from Amazon (a box of 6 pots is the cheapest) but at a premium price of around £14 for six which is over £2 per pot.
Hope this helps.